Am I about to lose the love of my life?

I’m a 34-year-old woman seeking advice or maybe a reality check. My partner, a 33-year-old man, and I have been in a relationship for three months, but we've worked together for the past two years. We were friends before, both married, so we never crossed any boundaries. Earlier this year, we both ended up separated from our spouses and grew closer while sharing our experiences. It started off with just casual texting, but it escalated quickly, and we became quite serious before we even realized it. I tend to fall hard and fast, but this feels completely different. I've never experienced such deep mutual love, understanding, or chemistry with anyone else, and he claims to feel the same. Currently, we are both separated. My situation is progressing to divorce, which will be finalized in January. I have a 14-year-old daughter with my ex-husband, and though things were rocky at first, we've established a peaceful custody agreement. My partner's relationship with his spouse has always been tumultuous, with reports of verbal and emotional abuse. They have two children, ages 6 and 5, and over the years, his wife has used the kids to manipulate him. This past summer, she took the kids to her hometown without informing him, and he feels threatened that she might permanently relocate with them. Recently, there seemed to be a truce where he was allowed more time with the kids, which was not the case at first. I have urged him numerous times to utilize our company’s Employee Assistance Program for legal advice, but he hasn’t taken that step. Recently, he called me in tears, expressing his desire to do what’s right for his kids and to provide them with a life he never had. He insists on giving his marriage one more shot for their sake. This has left me heartbroken, and he seems to be struggling too. This isn't the first time such concerns have surfaced; it happened around Thanksgiving, but nothing changed then. Now, he’s talking about moving back in with his wife after Christmas. Although I can’t share every detail without this becoming overwhelmingly long, there’s one more important aspect: I had an affair earlier this year, which he strongly disliked. I initially kept it from him but admitted it a few weeks into our relationship because I wanted to be honest. He has repeatedly expressed how much this bothers him and how it makes him feel like a rebound or merely “next in line.” I’ve done everything possible to reassure him that it was a mistake I deeply regret. I was with that other person for a short period, but it ended well before my partner and I got together. I’m not sure why he’s still so affected by it, especially since I’ve emphasized that it’s in the past. He has brought it up several times, and I can't help but wonder if he’s using it as an excuse to justify pursuing his wife again. I’ve told him I would love and care for his kids as if they were my own and that I would always be respectful towards their mother. He feels conflicted, torn between his responsibilities as a father and his feelings for me. He feels empty without one or the other and struggles to see a way to have both. He’s worried his wife might leave with the kids for good this time. My heart is shattered; I’ve never loved anyone like this before, even after a 15-year marriage. It feels profound, on a soul level, and he says he feels the same way. I can see the pain he’s in, but I’m unsure of how to move forward.