Advice please ..

I have been with my partner 3 years , both 28. It hasnt been easy at all the entire time. The whole beginning of the relationship I dealt with him secretly paying his exes phone bill and etc. Talking to her an what not well I found out I was pregnant so we tried to make it work... It worked and still is when it comes to him not cheating, but for a while now sex has been just horrible or non existent, all we do is fight and the communication is shit. Pretty sure he's a narcissist because he has a stank attitude and always starting shit but as soon as I react and get mad he pins it on me. we lost our son at 19 weeks pregnant over a year ago an things haven't been good since , they never were but they got really bad after that . I just really love him that's it , there's nothing else there nothing to keep us together. We are talking about marriage and I know it's just a dream it will never be possible, I'll never have a child with him because we don't even like each other enough for sex it seems. It's hard loving someone and knowing it's just the end of the story for you two . I have packed my things and left many times but I always come back. It's so toxic here we both know it. Physical , mental and emotional abuse daily. Lack of attention fr him I mean there is so many things it's heartbreaking. How do I stay gone when I leave 😕 I want to start a new life so bad but I just keep coming back, I've left state and everything I just have no clue how to go about it