My wife had an affair

First I found a text message, I confronted her, she had to admit she was having an affair, the reason she gave me were: that she believed I was having an affair,(I have never crossed that line) We were too tight on money,etc, etc and she started to cry when said that she felt I was treating her like a zero- for something I said on a fight we had. I started to pack my clothes when I saw she was really in pain so, I stoped.And my -Natrural rection to leave her, snapped--...We had a talk and decided to give it a try,... I wasnt all...Two day later she told me she had something else to tell me, and that if I would accept it she would do anything for me, Then she went on to tell me that  She was pregnant and  he's the father.I dont know what is wrong with me, but I forgive her, but this is been too painful, It hurt specially because we have two kids, and I love them more than anything in my life, I dont want to leave them without their mother but now I dont know if I doing the right thing.I gues Im terrified of leaving because  I myself grew up with divorced parent And I swore in my heart that I would never do that to my kids.