Rainer,
I have to be blunt with you... you are a dick head and softie to let yr girl run right over you and fxxk another guy. IF you had the balls to get aggressive and control yr girl and let her fantasy remained only a fantasy, today you wont be suffering. If it were me, and my girl insist on fxxking another guy to fulfilled her fantasy, I would hv kicked her ass and throw her into Chao Praya River. THATS the MAN she wans to see which she could not see in you.
Sorry I have to be tough to say the above but thats the way I treat my girls,and they simply love my macho demanding ways.
How can you still keep an absolutely unfaithful woman by your side even now??? I cannot comprehend. Good luck to you my friend.