My brother doesn't respect my privacy?

[Ashely Corner]

I respect his privacy. I rarely go in his room, I don't mess with his phone, I leave his friends alone, etc. It's the opposite for him. He always goes in my room, lays on my bed, and starts telling me a long story while going through my stuff. He always messes with my phone. One time I asked him to charge my phone while I was in the shower. He ended up texting my friend (pretending to me be) asking why he wasn't invited to a party. One time I left my computer open while I was chatting with my friend and he took my computer and started saying "I'm watching you" to my friend. It was someone I didn't know very well so it freaked them out. Just recently he took my phone and started texting one of my friends sending creepy messages. He does it just because he can. He got a facebook recently. He has been adding a bunch of my friends he doesn't know. They say he creeps them out. He randomly sends them messages informing them that he just took a shower or used the bathroom. He's not doing it to try to be funny. He has been talking to my friends on skype and oovoo too. I need my own friends. Since he got facebook it's like my stuff is his stuff. One time he had friends over and let his friends go in my room, break stuff, go through my bra drawer, and make a mess. This morning I was looking at my facebook wall and saw that he had gotten on my facebook account and added people I don't like. I left my computer open to go clean the kitchen for 10 minutes.

I don't know what to do anymore. I've tried keeping my stuff close to me but he always finds a way to get my stuff or go in my room. Anytime I go in his room he yells at me, yet he will come in my room, lay in my bed, and go through my stuff. Help? He doesn't have any mental disorders. I've tried talking to him about it but he acts like he has no idea what I'm talking about. He is a horrible liar. I know when he's lying. He gets a look on his face like he's trying hard to be serious and his voice changes. Sometimes he won't look at me or he will change the subject really fast. Help? He's a year younger than me. If I don't include him in everything I do with my friends, he goes crying to my mom and makes up a story that I yelled at him and hit him. She ends up believing him and I get grounded. Then he gets to go hang out with my friends even if they tell him that they don't want to hang out with him.