Sorry this is long, I need some advice on dealing with my difficult DF. Please help.
Backstory - DF always self and money obsessed. Set up and ran a successful business but refused to pay any of his 6 DC for working in the business and shafted us financially in other ways too. We received very little from our parents unless it suited DF so expensive holidays to places where his hobby could be pursued but he wouldn't spend money on clothes for us so we'd all be in our school shoes and wearing underwear instead of swim suits etc. After most of us had left home he self built an enormous mansion type house (We all did a lot of the work unpaid) in acres of grounds and started refusing to leave the house. He promised DB's the house was for them when he was too old to cope with it.
DP marriage broke down 17 years ago, his behaviour dramatically improved. He came on holiday with us a few times, was reasonable and made an effort and even sent cards/presents for birthdays etc. We started spending a lot more time with him and his new partner who we all got on very well with. In the meantime life went on. My DM met an American man remarried, and emigrated all within a year, this seemed to send DF into a tailspin. He was then diagnosed with diabetes and found out my oldest DB who had always spent most weekends at DF's house had met a woman and proposed. He suddenly and with no explanation, split with the long term (10 year) DP and was extremely cruel to her. Within 2 weeks he 'met' a new partner who was 25 years younger than him and had 2 DC. They were engaged within 3 months and married 2 months later (in a huge glitzy ceremony that was every thing he told us he'd found repulsive), and they moved into his house. He sent me a series of extremely unpleasant texts and emails telling me I had offended his DW and that I was behaving terribly. I had at this point only met her 3 times and everything had been cordial and polite - I literally had no idea where this had come from.
We were all very confused and concerned by his erratic behaviour (he'd always said he'd never remarry) but he refused to discuss any aspect of it. At this point I found out that he owed 3 of my brothers large sums of money from £12K-£75K that they had invested in land/house repairs/an extension etc. He fell out with his 3 closest friends and stopped pursuing his hobbies that had been his obsession. Over the next few months we realised that his DW was a heavy drinker and there were several incidents where she either passed out or became extremely aggressive towards my DB or their DW/DC - accusing them of stealing, swearing at her or assaulting her (all untrue). Her DC seemed to be nice children when I briefly saw them (they were made to stay in their rooms when anyone visited) but we were all told they couldn't visit us or meet anywhere as they would 'have a meltdown' or be bored.
DF made a concerted effort to persuade me to give him money at this time claiming they were about to lose the house, had no electricity etc. I stood firm and pointed out that he had 2 Mercedes in the driveway whilst I had a 15 year old Vauxhall and that his wife could get a job if they were struggling financially. He said she could not work as she had 2 children to look after which was a final straw for me. I am the same age as her with DC who are younger and have always worked, for some reason this changed how I felt and I cut contact with him almost entirely. He has continued to message me demanding I visit him and bring my DC, ramping it up for the summer holidays. I reply stating that I am busy and keep it very short. I do not answer when he calls me but text back politely but not budging. The final text is always a horrible insult from him - today "You miserable sour faced cow".
DB have had a mixed response. 1 is NC with him and has blocked him completely. Others see him occasionally, going to visit but not engaging in much conversation. They say the house is filthy and showing signs of neglect - broken toilets, leaking roof, appliances not working etc and that DF's health is clearly poor although he does not admit this. He recently tried walk around the garden with my Uncle and he couldn't make it without physical support as his feet were so painful. I am worried about him although he has never worried about me, even when I was in intensive care for 5 days after giving birth he simply told DH - 'she'll be fine, she's tough' and didn't call or visit.
If anyone has made it to the end of this long post thank you so much. If anyone has any idea of how I can deal with our relationship moving forwards I would be very grateful. I don't want him to die with things like this but also feel very angry with him for being such a poor excuse for a DF and behaving so badly. I have mixed emotions and often cry about this, it takes up a lot of head space. I don't know what I want or how to deal with any of it. Any advice is much appreciated.