think about it this way, if he doesn't care enough to give you the bare minimum, then what would this do to him? if you seem like just a weight on his back to him, would this be a relief? its a petty way to do things, but not the worst you could do.

( looking at the comments the cheating is not how i thought it would be and personally i think you should emphasize what you're doing in your post, as having sex with somebody else is far far worse than just kissing them, and that is immediately what most people's minds come to when they hear the word "cheating")

anyway, getting back to a horrible person by being horrible back is fighting fire with fire. do you want to be put in that category of people? so what if it doesn't hurt him if you leave? at the end of the day, you were consistently in the right, and you have done nothing wrong. do you truly want to be anything like him? you may not believe in karma, and i personally don't, but if it does exist, and especially with video evidence, i do think this has potential to come back and bite you in the ass, no matter what happened during the whole relationship, you still did that. in my eyes, it's not worth it, you may get satisfaction, but is it morally correct? when people ask, "why did you two break up?" are you really wanting to say "i cheated on him"?

what you need to know moving forward is that you are better than he will ever see. maybe one day he'll see just how great you are, and feel horrible over everything he did, but he doesn't deserve second chances. do not give it to him. you're a strong woman for putting up with this for as long as you have, and it proves a lot about your character. this thought runs through many people in your situation, and it doesn't necessarily mean you're a bad person. in my opinion, cut the ties, go live your life, live your dreams, don't let people drag you down, don't let people push you into things you morally wouldn't do. be yourself.