Need Advice

So my bf and I have been together for 6months. Two years ago his gf at the time died in a crazy accident. Since then he's been a wreck and slept around a lot.hes still friends with some of the girls and I've told him I don't like it so he's tried to distance himself. A while ago I found a bunch of old nudes from girls on his phone we worked it out but now I'm scared he's cheating on me. Idk what to do or think.