Do I stay with him or leave him?

okay so in my 4yr relationship there is no trust. when we first started dating i kissed few other guys, admitted it to him and he stayed with me. since then he has gone in chatrooms and adult explicit sites, exchanged photos with randoms, and called other girls (up to 5yrs younger than us, we are both 22) baby and all those sweetheart names.i found it all out on my own, he never confessed himself even when i confronted him he denied it until a day ot two later. now i understand he lost trust and thought i was fooling around still but i havent in over 2.5yrs. he continues to do it. on our bdayparty night out, i woke up to my laptop being on his msn calling sum girl bby. i freaked & tried to leave him.he smooth talked his way & fell into the same habits. i tried with him for over 2-3 yrs now.less than a month after ourbday i found a webcam site open on my lap top,confronted him about it, he said idk wat it is. i left him 4-5days ago now. he is claming 100%innocent intentions to try to work my webcam to take pics of us together. sounds like bull i have no trust now. am i doing th right thing and getting out?