Fiancé is suicidal

Im 18 weeks pregnant with our first. He's been really struggling with addiction. He can't seem to keep a job even since he's been sober.. He lost a really good paying job a month or so ago. He had a bad relapse last night and we fought sp bad. I said things I really didn't mean bc I hate when he's high and he brought up some things from 3 years ago when we first started seeing each other. He keeps saying he's not gonna live to see our babys face and he feels like we're better off without his 'worthless addict ass'. He's been sober for 6 months and just lost his mind last night. He won't stop acting cold and saying things like I need to hate him bc it'll make it easier when he does it. I keep begging him to stop and tellin him I love him and our baby needs his/her daddy and I need him too... He's been struggling with depression and thoughts like this for over a year while trying to over. come this. I'm so worried about him..

Please help me. No negative comments please.