"so i needed that proof that he was lying, so I can leave him knowing that I did try to make this work and I did try to support him, but that in the end, it was him that was destroying the relationship."
I agree, you may have been led on for a while without knowing. Similar thing happened to me, mine didn't think he would get caught then denied anything happened with his ex. Oh please, i don't want to spend my life wondering what/who he's going to do next. As hard as it is, your DEFINATELY doing the right thing
My thoughts are with you.