How to support partner in parents death?

My boyfriend is 28. He already lost his dad years before I met him and today he lost his mom very unexpectedly. He’s a recovering alcoholic from his dads death so I’m afraid he’s going to relapse. He has been doing so well. I’m 19 so I’ve never had to deal with this type of thing with some one else. Ive only lost a grandparent before so I can’t connect with what he’s feeling. His mother was also helping him with his rent that he definitely can’t afford while he is transferring jobs. So that’ll be extra stress on him. When his dad died he told me his girlfriend dumped him because she couldn’t deal with him and how he changed due to that. I don’t want to do that to him again but I don’t know how to help him right now. Any advice?