Dear friend,
Yes. People can be heartless. I was in a 4 year steady relationship with a woman, went away on business for two weeks, and she began an affair with a man on line while I was away. When I came home, we made love, were lying in bed afterwards, and the phone rang, and it was him. She whispered and giggled in conversation while lying next to me, as if I weren't even in the room. I was very hurt and angry, and told her so, and how could she show so little respect for me. She replied she'll show me respect when I show her respect. This is the woman whom I showered with love and attention for 4 years, loved her children, her pets, her home. That was in February. I left and never went back, and it still hurts sometimes to think she could have been so cold and heartless. She began a realtionship with the man she met. He told her he loved her, wanted to be the 'Dad' to her kids, take care of her for her life. He then went to Chicago, and never called her again.
My advice is for you to take some time for yourself. Excercise, eat right, and worry about yourself. The time will come when you can give love to someone else again, and you'll move on.