How can people date people with kids?

Before you bash me for the title question, I promise it's probably not what you're thinking. It's been a few months since I've had a little girl ripped away from my life and my heart is still broken over it. Her mother just quit taking my calls/texts, then eventually I noticed she unfriended me and my family on Facebook. No explanation, no reasoning to do so, just cut me and several other people out of her life. I don't understand why, I was always supportive and helped her out when she needed it. Her daughter and I bonded, it was mutual, so I hate to think she misses me too. I don't want her to feel the same loss I feel. She's still young, so part of me hopes she doesn't still ask mommy where I am or why I haven't come to see her. The selfish part of me hopes she won't forget me. How can you get over the heartbreak of dating and breaking up with someone for a good period of time that has kids? It hurts to know I'll most likely never see her again. I'm honestly afraid to ever date someone with children again.