Problem with grown up children after break up with their mother in 2003

I have 4 children to my first marriage. My eldest 2 sons (28 & 30) and daughter (16) don’t want to know me anymore and I have received extreme insults from my 2nd Son. My 3rd Son aged 19 is in the middle and doesn’t think the same has his brothers, so he stays and doesn’t want to compromise them or me. I feel so hurt and much rage! Story: Me and the 4 children’s mother broke after 20 years in 2003 after their mother starting messing around and got caught whilst I was away working. She ran off with the 3rd or 4th guy to marry him in Tigana without telling the kids and denied it when confronted. She brought this man into my family home when I was away. Although messed up I started another relationship in 2003 and got married end of 2004. Then ended up in another relationship (probably because I was so messed up. Had 2 more children in each relationship. My ex partner of 20 years moved out of the family home with her new husband in 2006 and my younger 2 children from that relationship went with her. I kept the house and a roof over my 2 eldest sons heads until 2014 when they were grow up. They now live in their own homes. In 2010 my eldest son moved out of the house and stayed with his mother and friends etc but that did not work out. He then stayed at my 2nd sons house for a few days but that not work out (suspect my 2nd Sons partner didn't want him there). Whilst I was abroad living my 2nd Son gave the house key to my eldest son without running it by me first so when I came home and discovered he was there with the place in a bit of a mess I was not happy. I was upset with my 2nd son for not consulting me first and I requested an apology which was not forthcoming. There have been other issues relating to disrespectful behavour by my 2nd son eg. He took my fathers photo from the kitchen notice board of my house without my permission. etc When I moved back to the UK house in 2012 with my new family (one of them, now of 10 years and I am married) the other estranged (but I still stay in contact with the kids). So in total I have 8 kids. I was staying there with them and my eldest. The problems with my family of 20 years caused many fights in my current marriage because we struggled for money for many years because I kept the uk home over my 2 eldest sons heads and paid the mortgage an bills which left us short. Anyway, things appeared ok with my eldest between 2012-2014 when he lived with us, I supported him and helped him when he moved out to his own place. But since he moved out (I don’t know where he lives) he has just ignored me and when I fell ill didn’t even ask if I was ok. Only my Son of 19 asked if I was OK. I am still in contact with him and we are ok. He tells his dad he loves me and I try support him best I can. My daughter sent me an sms at midnight one night saying she hated me for what I did to her mother. It hurt me and I told her to FO. I have tried to communicate with my children via email but all I get is attitude and abusive insults of the worst kind from my 2nd Son. I have done nothing to them to justify such extreme abuse like pond scum, scumbag, lonely old twisted freak (all this from my 2nd son). Now my 2nd son is expecting a baby and he has said that I will never know my grandchild and his children will never know me. I never harmed them when they were kids, never hit them, supported them when they needed and worked hard to get them into a good position to progress through A levels etc but my eldest 2 fluncked out after 1 year of A levels. Stuck my neck out for them when needed as loving fathers do! Their grandmother has confirmed their mothers messing around confession to them so the truth is out regardless of whatever their mother has said to them. And I fear she has poisoned them in some way. On top of all this I nearly died in 2002 due to DVT and have had to go through medical litigation in 2003-2005 which failed 2 days before trial. I ended up with 250k pounds debt. And it took me 10 years to clear it. After me and their mother split I maintained contact with them whilst living abroad and always asked how they were doing, showed interest and never forgot their birthdays or xmas. When I came back to the Uk in 2012 to stay I continued that theme until the sms message from my daughter. Prior to that she would come over to the house, sms me if she needed any money, I would ask her to come round for Sunday dinner etc. We had a Barbie and they all came before this sms. Then it all seem to get worse. One recent incident involves my 2nd Son saying I was vile because I responded so strongly to his sisters untrue and hurtful sms so I told him he was dead to me. Then I receive an email from him in which he states that I said that to all 3 Sons which is totally untrue and I had to sent a copied of my original email and his to the other Sons so they could see it wasn’t true. Note before their mums cheating we were a happy family that enjoyed holidays away together 4 times a year. I though I had brought them up decent as I was!! I had a fall out with my mum but sorted now and my 2nd Son tried to suggest that I was only interested in my mum for self gain and suggested my mum was lying about his mothers confession and stated that I had brainwashed his nanan. His nanan has since corrected him on this but is shocked at his abuse of his father. She says this is a side to him she didnt know was there. And previously she always spoke well of him. Now she does not want to speak to her grandson and tells me to forget him. I forgot to mention that he recently told me to FO and DIE!! Now I have lost 3 of the 4. I am so sad, so angry, so frustrated and depressed. With all sorts of crazy things going around in my head. What on earth can I do? It seems like nothing!