uptdate about my gf

That's a tough one. Getting it out in the open would be the only hope for me.

Either I couldn't trust her and it's over or we talk about potentially opening the relationship and maybe your fantasy becomes reality
 
the thing is that i can trust her anymore
Yea sure but just like ask her if she is a dick and if she said yeah then say why. If she loves you but wants to fuk others then sweet if she doesn't love you then just ditch man. Doesn't matter what age you are there's always another body that wants to hang out.