Electric Lights, it really doesn't matter who is in enabling mode, unless it's YOU!
Here's a thought to ponder: who makes better, more sane, more liveable decisions: your mom, or your abf?
I grew up with an alcoholic father, and as my marriage of almost 20 years is ending, to my horror, I am realizing that I re-created the dysfunction of my childhood in this marriage. From my experience, this is NOT something that you want for your daughter; this is NOT something that you want for yourself.
Here's another thought to ponder: you are a mother, a daughter, a girlfriend, and you are an individual with your own future ahead of you.
What are the obligations and responsibilities of all of those roles? And, how do your prioritize which obligations and responsibilities are the most important?
It may help you to try and step back from the immediacy of this situation, from the "noise" of your abf and his enabling father, and take a long view of the long future ahead.
This sounds like one of those pivot points that comes along only a few times in your life; the road you take now will open or close many doors in the future.
Keep posting, we're all rooting for you.
BothSidesNow