Most Helpful Guy
I would say you feel guilty because in your mind you are thinking "What did I do wrong? How could I have stopped this? or What could I have done better?". Don't feel like this, he cheated on you and the only person responsible for his actions is him. No matter the reason he did it it is NOT your fault! Are you married to this guy? If your just his girlfriend then dump him now. Once a cheater always a cheater I say.
Most Helpful Girl
Hi! Feeling low is extremely common and totally acceptable. Feeling guilty, however, is not right. You have done nothing wrong at all. It's your stupid ex, who's gone and cheated on you instead of coming clean about maybe being attracted to someone new and just ending things with you first, before pursuing him/her.