Advice and opinions please

I met my partner in December last year and within 2 weeks I let him move in things were great and I discovered I was pregnant, sadly we lost the baby but I got pregnant again straight away. My partner got a job but within 3 weeks he stopped goin and it caused arguments so I asked him to leave. He went straight back to his ex who he was with 3 years and he had only been broke up with her a week before we met. During argumentshe always said he would go back to her. He was gone for 3 months and we didn’t really talk in that time but he came to my scan and we got back together. He was back for a week and he left again in the middle of night and went back to his ex. He blocked me and I had no contact with him for 5 months. I rang him near my due date and he came to talk we got back together and he moved back in. I made him block his ex and things have been good and we now have our son. I’m just concerned he will leave again and also think he could possibly only be here for our son. He lost a son with his ex and he has always wanted a son. He told me his ex means nothing to him he was only with her until I wanted him back but I spoke to her once and she said he always threatened 2 leave her if she didn’t bring his child. We have

It's clear he's trying (and failing) to honor his sense of obligation to you and your child. You (and your child) deserve someone that willingly and happily chooses to commit to you and your child, without resenting you. But right now, you need to end it. Stop putting yourself and your child through the uncertainty and upheaval. A split won't be easy. Utilize whatever support network you have. Move on and stop all the chaos. He can honor his obligation to the child with child support and coparenting, regardless of who he's using romantically. Find a family law attorney, and start taking care of yourself and your child, instead of waiting for him to run back to his ex. Again.