Jealousy

I get really jealous when my boyfriend talks about his ex & still has photos of them together on his phone. Seeing photos of them together makes me really lose my self confidence. I know he doesn't still have feelings for her (& she has a new boyfriend) but she seems to snapchat him all the time & try to get to know him again. I don't want to mention anything to him, in case he thinks I'm being psycho. I know that he wouldn't cheat or anything, but I can't help getting really jealous.. Is there any advice any one has??