Next Boyfriend....
say no way
No, of course not
how do you know if your boyfriend has cheated
Sounds like you need a better boyfriend.
tell her that her boyfriend cheated on her. she needs to know.
She probably feels bad after what she did to you. Even if you now hate her after what she did to you she feels the same way as he was her boyfriend too
It is clear he must have a cheating problem so you should leave him alone
Dump him
you go and tell him you cheated on him and tell him how sorry you are and ask him to forgive you.
It could be nothing, or he could be trying to get information out of her. You have no right to be sad or upset because you did the same thing.
There is no way to positively know if your boyfriend has cheated on you unless you catch him or he tells you. There may be some signs such as not being where he says he is or lying to you on who he was with.
break up with him