How can I help?

Danielle
I'll try and make this as short but as accurate as possible. My partner had a friend, they were friends since school, we used to hang out with him quite a lot and he seemed a bit of a liar, well a lot! He loved about trying to kill himself more than once and was rather disrespectful, he also had a habit of using his diabetes as an excuse or playing on it when he was being naughty (for lack of a better term). He was with a woman and they had two kids together. More than once she had to ring my SO to go round as hos friend had gotten abusive towards her and the kids (she already had two). The last incident was the worst. She had a broken leg and he was stomping on it and throwing stuff at her, he even hit her. My partner was there and tried to stop him so she could get her and the kids out of the house. They managed to escape and she is now pressing charges. My SO had to give a statement and he has pleaded not guilty so this may go to witnesses etc. She has videos of her ex partner threatening them and threatening to kill the kids on multiple occasions. However the 'friend' is now in another relationship and his partner is pregnant, my SO has mutual friends with the abuser but they have stopped talking to my SO because he 'betrayed' his abusive friend. He is so lost and lonely and can't understand why they are on his side. I don't know what I can do to help him. He has been through counselling for the trauma and can't remember a lot of it as it was painful for him. He knows he is doing the right things and I try to support him as much as I can but he feels so alone now he has lost his supposed friends. How can I help him? I don't want to see the amazing man I have slowly lose himself to this when he hasn't and isn't doing anything wrong. Sorry it's long, I tried to shorten it... I'd be grateful for any suggestions/responses you have. I don't know where else to turn. Tia x