Disappointment

I've been disappointed before, in myself, in my friends, in decisions, but I've never quite been disappointed in a family member. For the sake of anonymity I am not going to go into depth of the situation but more of the feeling. It's a heart wrenching feeling. Like being back stabbed. Like being pushed down to the ground and getting kicked when i was powerless.
I'm use to being put down, either by rumors or what people did to me, but this family member (let's call her Megan) use to do the same thing in a playful manner. She was practically my sister and we did as much as we could together. When I entered high school as a freshman, Megan was a senior. Of course I thought maybe she'd be my mentor. On the contrary, she was more of a temptress. Luring me into the dark side of high school. This was a very disappointing side of Megan I never wanted to see. It died of course, but to think that she was so close to me, meant to protect me almost, and she was trying to get me to make the wrong decisions in life.
Decisions, it's another thing I'm not very good at. I've had to failed relationships that were quite similar to each other yet different. However, the signs were exactly the same. More heart break and stupidity. Even with how I dressed or what I day affected me. At some point, it was like no matter what I did, good or bad, people were talking bad about me. It even followed me to high school. None of it was true, but it still hurt to know that my own peers were trying to sabotage me and disallow me from meeting people without them thinking I was a whore or "skank."
Even my closest friend succumbed to the crowd and left me in the dust forgetting I even existed or that we had already gone through so much together. Since then, I have not made another best friend that is a girl. Girls seem to just want to compete with each other. I'm not really interested in that. They are and in order to make themselves feel/look better they put me down. Okay, I'll take your hit, but I just wont show it off to the world. I'll keep inside and let it pain me. Burn me from the inside out, it's a consequence I'm willing to tolerate instead of falling into the same trap.
Clearly, I'm one to state my opinion. Good or bad, or even offensive. If I have something to say I will say it whether you like it or not. I've been told several different times to stop expressing myself, well, if you don't agree, don't talk to me, stop following, don't look at me, talk to me, or even think about me again. It's your choice. My decision is to tell the world my opinion same that everyone does at school by spreading rumors only I'm not purposely ruining anyone's reputation.
When I'm told a secret that is not what I expected or not a good thing, I'm not angry, I'm disappointed. Taken Megan for instance. When she first admitted to me that she did a lot of bad things (drugs, alcohol, sex) I was really disappointed, but she was practically my sister so that disappointment grew to concern. Luckily she changed or I would have lost it if something bad had happened to her. Now, I feel like I don't know anything about her. Megan fell off my radar, yet she's coming back and I don't know how to handle it. Anytime I see an old photo I'm hurt at the thought that she left me in the first place. We had so many memories together and it felt like she threw it all away. Does she expect to come back to open arms? Sorry, you're going to have to tickle me in order to get a hug because I am not in any mood to be trifled with.
Everyday she's gone, she put farther into the darkness. Every time she's mentioned, I'm annoyed. Anytime I miss her, I'm disappointed. I don't expect disappointment to disappear but I hope it dies down a bit. Too much disappointed could lead me into darkness and I don't know if I'm strong enough for that. Give me strength.