Should I smack the Sh*t out of him?!?!?!?!?

So my bf left for a little while and he let me use his computer. I went to facebook to check my profile and he was still signed in...i know i shouldn't have looked but he all these messages to girls about , and one girl was like i cant believe you don't have a gf and etc...should i approach him or what...or am i wrong for being nosey?