I am a bad person. A horrible person. I curently hate myself.

I am in my early thirtys and have been with my husband for a decade now. we have 4 kids together. I have been honest with my husband that I am not happy and he sort of trys to make it work. he does the bare min I ask of him. He swears that he has never cheated on me but I have found panties that are NOT mine. A female friend of his spilled the beans that he has taken her out, they swear that it is just friendship but you don't take a friend to a fancy dinner and a movie, then back to her parents place for coffee. But that doen't justify what I have done.

I am in a highly intensive medical training course thru collage. Study groups are compulsory and they are assigned. There is a Man in my group. A really great, fun, crazy, supportive, creative, amazing man. Not to mention extremely attractive. He is the same age as I am and single. We have been getting close, but I have been close friends with men before with no temptation to cheat what so ever. I have never ever cheated on a man in my life. Never even come close or been tempted. But this man. This man Tempts me. Yesterday I went to study at his place like a thousand times before. Our other study partner couldn't make it for what ever reason. We were down on the floor looking at flash cards, when he noticed that I was having shoulder pain. He started rubbing my shoulders, which he has done before. After he finished loosening the muscle he lay down next to me again. earlier he had won a bet as to the correct answer for a question. He requested his boon. He said, "You know that bet? I know what I want, just one." "one What?" He leaned in and kissed me. it was nice. Really really nice. I should have stopped him, but I didn't. After, I said I needed to step outside for a cig. I really needed to get away. We went back in after out smoke, and like a whore I let him kiss me again. This time he pushed me over and kissed me from above. he pressed into me. We got a bit carried away, but I put a stop to it in a panic. We didn't cross the ultimate line, or even go under the pants.

What is the worst is that my husband trusts me completly. I have never given him a reason not to! How could I do this to him, and how can I keep myself from doing it again? I really really like my friend. Way more then I should. I told him this can never happen again and he agreed. He was so upset that it happened too. He isn't the home wrecker kind of guy, but we have a connection. I hate my self...