Is there anyway to make up for breaking this girl's heart?

I broke up with my ex a long time ago but I am still not over her yet because I was deeply in love with her. I stayed single for a good 2 years, but just recently, I treated a girl who liked me badly and I feel kind of bad about it. I met her at a house party, her friends told me she liked me, and so I made my move. I dated her for a good 3 months, and then I had enough because there was nothing there. I didn't even like her, I just wanted to get over my ex so bad so I just dated her out of desperation so to get rid of her I asked her to meet me at a restaurant, and I never showed up. I apologised for standing her up, and the next day I had a one night stand with her friend. I then ignored all her phone calls and text messages. I don't know why I did it, maybe because I didn't want to go through another breakup again. It gets worse because my sister found out because she had a mutual friend with my sister, and my sister slapped me for treating her this way, and isn't talking to me any more. My sister said that she doesn't want to know me because of the way I treat women, especially since the girl apparently really liked me. How can I make up for what I did?