Please feel free to comment on the first three in my series of immorality questions if you haven't already. Here's Part 4--were my actions immoral?

I was living with this woman, Maria, for about 2 years. She was very pretty, but she was not very bright nor was she interesting. Honestly, the only reason I had her around is because it was a low point in my life and it required almost no effort to please her. She was, however, extremely annoying at times.

Anyway, one of her girlfriends became a go-go dancer and Maria was appalled. She said that she no longer wanted to be this girl's friend. One night, I secretely went to see this girl dance and I told her why Maria wasn't talking to her anymore. In fact, this girl and I made out in the VIP room and went away together the next weekend.

I told Maria I was going on a fishing trip. I had insane sex with her ex-friend all weekend and we put Maria's picture on the night stand. We laughed hysterically the whole time. Immoral?