Sad today

I am having a hard day today. Mostly just sad. I can't figure people out. I can't figure out, how they work. Why they do the things they do. I am close to no one. Absolutely no one. I never could figure out, why I don't let people in. More and more me not letting them in, does me more good than bad.
When I had Savannah, I was going to stay at home with her, til she went to school. So I took in a couple kids to watch and did odd jobs, hair, etc on the side.
All of my family knows Maddie May. I have had her since she was a baby. We kept her every single weekend. She would stay over night. She stayed weeks at our house. Almost every holiday. Every Halloween. I loved her.
Well, as you guys know, her mom hasn't treated me the best. Especially for all the things that we have done for her. Taken her on our trips, spent our holidays with her. All of it. :(
Well, over a week ago, her mom told me Maddie would be here Wednesday, Saturday and Sunday. She didn't show up Wednesday. No big deal, with them that happens alot. I never say anything, because Savannah loves Maddie so much. I didn't want to strain my and Karens relationship so that Savannah and Maddie can always be friends. I knew that when they both started school that Maddie would quit coming. I just figured even though it was never talked about.
Well, I called to find out where Maddie was and when she was coming back and her mom just up and hung up on me. No hi, bye, kiss my ass. Nothing.
Be an adult, tell me she won't be coming back. Now, that she hung up on me, I'm extremely torked off. I did nothing. Never have been rude despite all the rude things she has done. So now Savannah has lost her best friend. Almost 6 years of them being inseparable. I am used once again in my life and tossed aside like garbage. Why do people take everything they can from me and just leave me? It's hard not to be sad. I had a part in raising her. I loved her.
I cannot for the life of me figure out why people use me so much. Maybe I am an easy target? Maybe people see doormat written on my head. None the less, that is exactly why I tell no one anything. Why I share nothing. It's easier in the long run. If you tell stuff, people generally use it to come back at you later. Gotten a good dose of that with several people. I've gotten too many doses of alot and can't figure out why. What you see with me, is what you get.
In ending that, I don't know what to do as far as trying to figure people out.
Absolutely do not understand meaness, hatred, using.
Things on my I do not understand in life list.
Happy Wednesday.