Maddoc----breakups are hard---but, you are making it harder than it has to be. This means that I will be repeating myself, but, I will do it again.
You are making it harder to stay away by the following things, I think-----triggering bonding hormones by the horizonal tango/intermittent reinforcement (the most powerful kind00google it)/and drinking alcohol which lowers ones inhibitions.
Horizonal Tango----causes the release of oxytocin----the powerful hormones that causes even mothers to bond with their newborn.
And, the wonderful doopamine----the neurotransmitter that causes to seek and repeat pleasurable actions. It acts, mostly on the pleasure centers in the midbrain. It causes us to seek food and entertainment or just about anything that gives us pleasure. Especially food and sex! Same, with drugs like cocaine, etc. It is very active in all addictions. including alcoholism.
Every tune you interact with him, that is intermittent reinforcement, after you have blocked him. You can google it---as it is the most powerful kind of reinforcement.
Drinking with him-----the alcohol releases your inhibitions, and you will be more likely to do things that your sober self wouldn't do. Like slapping his hand. Or having sex when you wouldn't usually. This is because the alcohol interfere with the frontal lobe of your brain---where the executive functions reside---reasoning, judgement, planning, etc.
All of these factors, added together, are setting you up for the kind of evening that you just described.
I am glad that you are seeing the counselor, because there are, as you say, dynamics of why you are attracted to this guy. the list of potential factors is, likely, quite long-----
You might want to read the long post that Velma wrote to Ituvia this morning, about relationships....it is quite good.
I will, also, be looking for another song to dedicate to you.