Okay this is making me freak

Ashlee
So my boyfriends phone broke while he was on vacation and at the moment we are doing long distance. He wanted me to log into his snapchat and keep our streak going so i said I would. A few weeks ago he told me that the girl that put him through hell and screwed him over with his emotions and trust and cheating on her boyfriend with him texted her and said she needed a friend. I told him that she lost her chance and then I said whatever as long as she doesn't try anything. And today I was checking his snapchat and SHE TEXTED HIM! Idk what to do. Should I bring it up to him or should leave it alone???? Please I don't want to be that kind of girlfriend. And the thing is, the girl is one of those that cheats on every boyfriend she gets and Goes around with everyone she can get with... That's why I'm freaking out. They almost did it! My boyfriend and her! Idk what to do!!!