Well, it's very tough situation.Everytime when between two people comes a third person it means troubles.I can tell You some advices.Personally I think You should wait few weeks,now he may reacting too emotionally.He may feel hurt ,of course if his feeling were for real.And You should know that next few weeks are going to be very hard to stand.Be brave girl
You can also go to him and try to tell him how much You care.But wait few weeks for that.
And about this girl... She must be stoned or CRAZY in love.Some girls are feeling so inconfident that they are acting like this.And tell her she's a whore,even worst because she's a damn crazy whore
One time my ex received an e-mail from a girl with her naked ( well it was porno) pictures and I've checked his e-mail before him.I asked him one time what is this.He told me he knows the girl but he don't know why she's sent him those pictures.So I've sent her an e-mail from my adress "Stupid bitch" . She never wrote him back again.She didn't ,I've checked it
So girl.Girls can be really stupid.And trust is the most important thing in a relationship.No trust?No love.Of course it's nothing bad to ask.But not 100 times.It's always better to be the good one,belive me.And after winter must come spring.People sometimes need to have their bad moments that they can appreciate the real happiness .