Potential boyfriend’s past relationships

This guy I’ve been getting to know told me last night when I asked him about prior relationships that he participated in an affair for two years with a married woman. It has been one of his longest relationships. For me, this was a major red flag. I’ve had opportunities to help a man cheat on his wife before, but have declined these invitations and have been wondering why so many people find it so difficult to avoid these kinds of inevitable shit shows. I’ve had low self worth in the past, but that never guided me toward affairs, but it did guide me toward a dysfunctional marriage. Anyway, he told me he ended it with the woman, but it just doesn’t seem like he’s had long-term relationships with anyone who is truly available. I’m nervous that he’s going to fuck this up somehow. He also has a DUI in his background and just kind of lives spontaneously. Not a huge issue for me, but the potential for infidelity makes me feel like all I can reasonably offer him is a casual/open relationship while I keep an eye peeled for someone better. He has remedied some of his past faults, so I do give him credit for that. He’s open and honest about his past even though he’s not as self-aware as I’d like him to be. When he told me about the affair, I refrained from openly judging him because I wanted to understand his point of view. He framed the story in a way that made it sound like he had no choice to participate in the affair because the woman made the first move (WTF?). Anyway, I listened even though I was disappointed and seriously re-thinking my involvement with him. He wants to meet me in October (he lives several states away) and I’m trying to find a way to back out of this. I am not all in and I don’t know how to be. At this point, my thoughts about his past choices are scaring me.

C: J tells me his most recent relationship that lasted more than 2-3 months was an affair that lasted two years
T: This is a massive red flag about his character
F: Wary
A: Try to think of all of the good things about him, wonder if he’s a player type who only has relationships with emotionally unavailable women, wonder what the fuck was going through his head, wonder about his ability to adhere to boundaries, start to emotionally pull away from him
R: Go back to the dating app to find someone else and re-start the getting to know you process with a new person

C: Same
T: He might have grown past this type of behavior
F: Reflective
A: Consider the possibility of an open relationship with him, ask him about whether he seriously thought about developing a relationship with this woman, ask him about his tendency to go for emotionally unavailable women, ask him about whether he’s dated women locally
R: Learn more about his thought process and become emotionally unavailable to him (great he will chase me even harder now, lol)

I want to find a way to salvage this, but that’s mostly from fear that I’m not doing thought work correctly around this and because I judge myself for judging him. We have had some good conversations and I feel like there is a budding connection, but I’m still unsure at this point and have been weighing investing more time and effort in him. I don’t even know if emotional availability is a ‘thing’ because you could find evidence to some degree that anyone is emotionally unavailable.