My world is falling apart


I was with my husband 7 years he was my soul mate. The best man ever ! I trusted him with my soul an amazing dad too. Well everything changed 3 weeks ago he fell into depression Gave up on life completely. Quit his dream job. Cheated on me. Has become a bad dad. Drinks 24/7 comes home at 3am every day. His mother & siblings are people who are never happy for him Idk ? They just always think he can do better? So when he has got a good job they never congratulate him just an okay so ? It takes alot for them to show love to him. so He thinks being the fuck up they all think he is will Some how is going to do anything. He’s a completely different person. I have asked him for a divorce and to leave our home because all though I Love him & care about him He won’t take my help so I refuse to live this way. My question is should I let his family know how bad he is ? They love him I’m sure I just don’t know why they act that way towards him. I know they would help him if I spoke up but idk if its my place to let them know what way he is headed. I believe if nobody helps him he will end up killing himself he has said it lately.