Thank you everybody for your replies and for giving me perspective.
First, with regard to the photo, I asked LB about it - I hadn't met his mother, so asked who was in the photo with DD. I don't think it was intended to be cruel. It was one of a number of photos displayed on the window ledge, which included photos of DD and LB at their graduations and even one of DH and me and our families on our wedding day - I didn't even know that she had it.
Gutterton - I agree that it is not useful to share our hurt with DD right now as, if she acknowledged it or accepted that she had 'wronged' us in any way, it would be going against/a betrayal of LB, who has taught her that she is right to treat us as she has done. It was clear on day 1 that he is still nursing a grudge from when I made him leave our house - five years ago now - after he seemed to be bullying DD and she had locked herself in the bathroom to escape him. This was not a 'one off' - she was crying and upset an awful lot at that stage, which is why I was so worried about her and about the relationship. Now she just says that she had mental health problems at the time. I said on day 1 that I didn't know about mental health problems, that I acted upon what I saw, it wasn't personal although it must have seemed it, I was trying to protect my DD, as is a normal parent's reaction. There was no commitment to meet up again and we will be unable to make any plans with DH as he is, in any event, without the added complications of the virus. I think LB had probably decided that we have had our visit now, and that's it. I am happy to leave it for now, anyway, it was all a bit of a strain, to be honest.
Sushi, Random, billy, drama, mcmooberry, 5LeafClover - thank you for your comments and kind wishes for DH. Upon reflection, perhaps LB's parents were possibly a little lacking in tact, although I can see that the meeting was potentially very awkward for them too. Actually, LB's father was lovely and his mother seemed very warm and friendly too, so the initial reaction was one of immense relief. However, thinking on it since, there were a few comments which were a little insensitive. For example, they know that DH has cancer and is about to start treatment but LB's mother asked if we were planning any holidays and I said not until after treatment. They said that they knew someone who had the same cancer as DH, who had been treated with a stent, which I assumed to be a positive and encouraging remark. I said, 'Oh, how is he?' - answer 'He is not with us any more, but it worked for a while' - short embarrassing silence.
LB's mother didn't just say that she regarded DD1 as a daughter once, but three or four times, and also said she was 'a credit' to us, which I am sure she intended to be kind. But she kept telling us how DD and LB have a wonderful family, are amazing parents, they wouldn't be surprised if there were more DC, how hard working and entrepreneurial they are, how they will be successful at all they do etc, etc. It was almost as though I was being 'sold' this account of my own daughter - maybe they think we don't appreciate her.
What was slightly more hurtful was LB's mother's statement that she thought that it was she who had encouraged my DD to apply for the PGCE. She may well be right, as she teaches PGCE herself, but I did think that we supported DD in her education as well and will be giving some support for the course, so we are not totally irrelevant.
With hindsight, I think that LB's parents were very much sticking to a script, whereby they said positive things, but didn't venture into anything controversial. I did say, as it seemed a bit unnatural not to say, that we hadn't known of DGD1's existence until recently, that DD1 hadn't spoken to us for a period and still wasn't speaking to her sisters, but we wanted to resolve things and move forwards. I didn't say it to have a big conversation or go into the rights and wrongs, but it would have been odd not to say anything. They just said it was all very strange, that they didn't know much about it (which seems unlikely, although I respect their tact), but what a lovely couple, happy family, LB and DD are etc. They studiously avoided any discussion of anything remotely controversial. I said that LB had not wanted us to meet them and LB's father said that he thought LB would have considered it socially awkward. He was a lot more sensitive than LB's mother, upon reflection. Obviously, I wouldn't have said anything against LB and DD but maybe, in their position, I would have said something along the lines of that must have been difficult, but hopefully all will be well now. I think that's what they meant to convey, but obviously it was difficult for them too.
The bottom line is that they have been supportive to DD and LB, so we probably do seem to be lacking in comparison. They live close by and the DGDs are their first and only grandchildren, and the paternal grandparents are also involved and adore them. They see them at birthdays, Christmas, New Year, all the time. They are a close family unit, which we are not a part of. I just need to accept that and be pleased that DD has loving in laws and solid support.
SirVix - I think you are right. DD1 is blithely unaware of all of the grief and pain she has caused. She really just doesn't see it, not only in relation to us, but also her sisters. It's not only family, but all of her friends, formerly close, whom she has just dropped without a second thought.
Fretful - LB's mother said several times how hard they both work and made no comments about LB's lack of a job. Apart from doing his PGCE a year ago, and a placement which he gave up early, LB hasn't worked since his graduation in 2014, but his parents see them as being highly successful and entrepreneurial. I asked DD how they were managing financially and it seems that she is being paid a bursary of £200 a week whilst she does the on line course in preparation for the PGCE, and is expected to do 22 hours a week - which she does after she has put the children to bed. She seems excited about the course, which I am delighted about. Unlike LB, she really wants to study. LB told DH that he had only done the PGCE for the bursary. LB's parents have always worked, although his father has recently retired.
Jenny - I think you are absolutely right that DD wants to brush the last couple of years under the carpet and sadly, I don't think our relationship can ever be the same, although hopefully it can be better than it has been. Thank you for your wise comments and good wishes for DH.
MaybeDoctor - LB is unsure whether or not he will do his qualifying year.
LadyEloise - Thanks for your support. You are right that DDs 2 and 3 are protective of us, especially now that DH is so ill. They are angry with DD1 and don't want anything to do with her at present. I think the stress has affected DH although he doesn't acknowledge it, just bottles it up, but he felt quite poorly at the end of that highly stressful day 1.
Random - I am sorry that your childhood wasn't happy. You are obviously a lovely and forgiving person. I think it is always better to forgive if you possibly can as, otherwise, the negative thoughts are corrosive.
Gutterton - thanks for sharing the article, you are never 'way off-beam' .
springy - thank you for your wise and comforting words.
Menstrual - I also wonder DD1 will realise one day that she is doing everything and resent LB's lack of support. She reminds me of a friend of mine, who was exactly the same for many years, but has now woken up to the reality, has no respect for and is in the process of leaving her husband - encouraged by her daughters, who see the way their mother has been treated.
Sir Vix - I am sure that you are right that LB's motives are entirely financial. I would go further and say that we have only been 'allowed' contact and this visit, because of the 'loan' and agreement to offer some financial support for the PGCE. In fact, the letter which they sent with the photos of DGD1 specifically says this.The question of finance was raised on day 2, presumably by prior design. DD1 asked me outright whether or not the 'loan' to buy the second house was a gift or a loan, in which case they would prefer to pay us back in one lump sum out of the bursary. I was pleased at the offer to repay, assuming it was genuine, and didn't resent getting things out into the open, as I know they want certainty. I drew DH into the conversation as he was at the other side of the room talking to LB. We said it has to be a loan, as we are unsure of our finances at present and you are one of three, so whatever we give to you we have to give to your sisters - however, we are not chasing it at present. With regard to the course, DD1 said she thought 'the deal' had been that we pay the rent when she does her course and we confirmed that. To be honest, I was relieved that they weren't asking for anything else - they are researching getting some government loan for childcare. I suspect LB's plan is to have childcare and stay at home, save that he presumably won't have any DIY projects to work on, as they will be in rented accommodation.
Sorry this is such an epic post, but I wanted to try to reply to everybody who has taken the trouble to respond. This thread is such a help to me, as it is invaluable to gain the insight from people with independent judgement and it makes me feel a bit more 'normal' somehow.