You know what I think? I think he's broken and bruised and in a state that when anyone at all shows him kindness he's going to imprint on them and think they have a connection and that he's met someone. I don't think he's a jerk, I think he's healing, and when you're broken like that you don't always know what you're feeling properly iykwim.
I agree with others who say keep well away, but it's not a reflection on you. I think he is going to keep 'passing over' women because every positive interaction is going to seem like it was meaningful and should therefore be explored. I also wouldn't be surprised if this new person doesn't pan out and he tries to come back to you/tries to confide in you about it.
Obviously you know him better, but based on everything you've said it is hard to believe he is just a jerk after all.
ETA @Bonezart did that muddled puddles thing come from your brain just then? If so, totally in awe of you...