I'm so sorry @Moira1951 that your son is not as close to you as he once was. There is, unfortunately, some truth in that saying:
"Your Son is your Son 'till he gets him' a wife, (but) your Daughter's your Daughter for the rest of your life".
I am also a Grandmother on my sons' sides.
Of course I don't know your DiL, and I don't want to talk about DiL's in general on here in the same way that far too many DiL's talk about their MiL's - with dislike, disrespect, and in fact what often seems to be hatred.
But to me the bells that are ringing are saying that yes you are right that you and your son were very close, but I am sad to say that many wifes appear to hate and/or feel threatened by that closeness. Of course your son should always put his wife before you - just as I expected my husband to put me before his mum - and I don't know if any blame (if there is indeed any blame) should fall mainly on your son's side for not making it obvious enough to his wife that she is the most important person in the world to him (until the baby comes along!), or whether his wife is more to blame for not understanding that her husband can still love you, without it being a threat to her? I am not missing out the fact that maybe many MiL's also might have to accept some of the potential blame, if they haven't realised or accepted that their son has a new leading lady in his life, and that that is exactly how it should be.
I think that your son has probably had his wife trying to demand the most and best of his attention - maybe especially since she got pregnant - because she doesn't yet have confidence in the fact that she is now his number in everything. I think that when your son is 'laying down the law' he is mainly doing his wife's bidding, and as that probably makes him feel at least a bit guilty to be telling you things like, what you are to be called by your new Grandchild, and then when he can see that he is riding roughshod over your feelings, it might make him appear a little cold/cross/grouchy because of that guilt.
All of you (includes your son and his family), and all of us, are only human. We have all had different experiences in our lives, we all have things that are more important to us than other things. We all have to make our own decisions and choices. I know that you already know all of that OP, but sometimes we need to remind ourselves about the things we know. Please do not always give into the things/ways that your DiL and now your son dictates, you should not let them control your life, but do, whenever possible give them a calm and reasonable explanation about why you are disagreeing with them on any given occassion, and just continue trying to treating them all with love, compassion, and understanding. I think as mothers and mother-in-laws we have to be the bigger people and not argue (angrily) with them, even when we can see that they are making a decision that we think they will regret!
I hope I haven't tread on too mamy Mumsnetters toes while typing this 🫤