OK well if you realise that's the main thing. Now you can start to work towards removing him from your life. If you're still getting lusty feelings when you see him then remind yourself of the quite extensive list of asshole things he has done.
Also from a hygiene and health view, the fact he sleeps around with an entourage of cheap slags means he may well pick something up, if he hasn't already. Even if you're using a condom for sex (which I'm pretty sure you will be, cos you don't seem stupid) it isn't 100% effective and there are others things..such as crabs that can be passed on regardless. I'm sure you don't want to catch anything so when you next go near him think of lots of little lice crawling all over your pubic region and you'll be very put off!
Ultimately you've made some dumb mistakes..but haven't we all? I was in a similar situation 2 years ago and it wasn't until my friend told me (rather like receiving a slap round the face) that I woke up. Telling the guy what a worthless asshole he is made me feel so great, so maybe you need to tell him that. Firstly cos it'll be enjoyable, secondly because it'll prevent you repeating the mistake cos he'll be out of your life. Trust me it'll be better for you once he has gone & you can chalk it up to minor brain damage! I laugh about what I did..so eventually you'll be able to as well.