Have You Ever Forgiven a Cheater?

please help me. I have never been this depressed and I fear it's going to kill me.  

I recently caught my boyfriend of a year plus now, right in the act cheating on me. With one of his neighbours. I had gotten a half day off from work that day and was in high spirits. So I decided to surprise my boyfriend. My plan was to go to his house, he was also supposed to be at work, he's a sales rep for a company. So my plan was to visit him, prepare a delicious meal, set up the house for a romantic, relaxing night rest and wait till he gets home from work.  

Since I had my own key to his house I just went straight to the market, bought stuff I
needed and headed for his house without calling him. I got there, as usual I opened the door and walked in. Only to be confronted with soft moans coming from our bedroom. I was confused! At first I paused but curiosity got the best of me and I headed towards the direction of the noise. What I saw made me nearly collapse in complete shock. My boyfriend was in bed with his neighbor, who knew very well about me. 

 He saw me and immediately got off.  I was speechless. I couldn't believe it! When I finally regained consciousness, I just quickly left, weeping and shaking violently. My supposed darling boyfriend chased me and was saying all this stuff how he was sorry and that she meant nothing to him. That it was just a one time thing. I was just screaming in shock.  

It's been two weeks now. My boyfriend has also cried his eyes out to me since I caught him, sent everybody imaginable to come beg me and won't leave me alone but the hurt and the pain of being betrayed like this has been too much for me to bear.  

Have you ever forgiven someone who cheated on you? Why did you take them back? And did it work out the second time? Are you guys still together? Or is forgiving a cheater something you would never ever do again? At this point, I don't even see myself in that house again. But I really loved my boyfriend. I really loved this man. Why would he do this to me? Why?! The tears won't stop pouring.