Is there any chance of saving my relationship?

I'm going to try to keep this brief. I'm going to be open and honest as well so please be kind.

I've been with my partner now for over 4 years on and off. Well, a year or so ago when we were staying in a homeless shelter he would not stop using drugs. Im an addict as well but I had stopped using and was trying to get my life on track. I hate being around him when he's on meth and so I was distancing myself. He would stay up all night talking to these girls in the shelter while I tried to sleep. I got a job and I started to feel upset because he didn't seem to want to get better. I had downloaded tinder but never talked to anyone or anything but he did see it on my phone. He's convinced I cheated on him during that time period but I didn't. After showing up to my work high on meth and making a scene, I got fired. I was so upset I left him and moved in with an old family friend. She was an alcoholic and to mask my pain I started drinking heavily. At this point I didn't think we were together. I did sleep with a few other people. But I wasn't myself, I was blacked out drunk, and I was also paid for some of the times. I needed money to supply my habit and pay for bills.

He was a sex worker as well in the past. Since I wasn't using heroin he doesn't believe that I mostly slept with those people for money. He doesn't understand alcoholism or where I was coming from. We weren't even together.

On and off I would see him and talk to him after a couple months. We never got back together during these times but I was always sweet to him and loving. So maybe he thought we were? I don't know...

Well fast forward to December of 2020. I was clean and so was he and we got into sober living. We got back together and he told me all was forgiven and forgotten. I forgave him for all he did too. March I fall pregnant. Now, July, I get us our own 2 bedroom apartment. All seems perfect. I'm pregnant, we are sober. We have our own apartment and he has a good paying job. We'll a couple of weeks ago he relapsed. He blew up and said he never forgave me. He brought up things that happened so long ago I moved on from it. Well, he lost his job, lied to his manager and said we lost our baby! He has used 2 more times and tonight I see he's talking to other girls and even met up with one of them today! He said it was to just sell her a pill but I dont believe it. Last night I was in the hospital with threatened preterm labor and when I finally got home at 4am he was gone. I have tried to kick him out numerous times. He won't leave. I tried to call police and he grabbed the rifle and put it under his chin. He hasn't slept in about 48 hours now and I'm so tired. I'm so heartbroken. I thought my life was finally settling down. I fucked it up a lot with my drugs addiction and past mistakes. But that's not who I am today. I even packed all of his shit and put it in the living room but he won't leave. So can I salvage our relationship? I've told him we both need therapy as well as couples therapy. But he just keeps making me feel like shit for "giving up" on him when he's just battling addiction. But this is much deeper. I just want to start healing. My baby girl is going to be here in November. I don't have time for this shit. I need to be strong and stable for my daughter.