Oh Meadow - I can relate, like others have shared. I too had a hard time completely ending things with someone very much like you describe this man. Things ended up escalating until I had to file a restraining order which he repeatedly violated, and go to court. It was horrible for everyone involved (including HIS children; I don't have any).
I'd encourage you to be what I would describe as brave and end things completely, despite the very real and understandable sadness. I have found most emotions to be complicated, and especially so in a couple of bad relationships, until I both got sober myself, and became a person another healthy person deserved. That last part is up to him, if he can - but you don't have to wait around and hope he does or try to help him, which most of us find we ultimately cannot....
There are links and threads here - as well as IRL groups like Al-Anon that are meant for the family-of/people connected to alcoholics (that's a slightly different part of this discussion, but he does seem to fit that based on your shares). It is really helpful for those I have known who needed support for themselves.
I'm glad you are sharing here and if you meet him today, I hope it is not in private so there are best odds of in person civility....and my hope is that you find some real distance for yourself and your child.