Since I'm really shy my friends don't notice me as much and when I start middle school I want to start new, like suddenly after two months I'm actually not shy anymore. But I'm not sure how do that and what if I leave them will they tell all my secrets. So I need help and fast.

Hmmm. Well if you leave them. They may tell people your secrets. Have you ever considered when you start middle school, you can make new friends? I know that's leaving your old ones. Have you ever thought of talking to new kids? Or kids who look alone?

You do not actually need to share all your secrets with all of your friends.

When you have one special friend or a best friend,those will be the ones to share secrets with.The other friends you can just have fun and be with them.

Read up on different things,like a new sport or information related to subjects you are interested in school or out of school.That way when you meet new people and you find out their interests you will have some knowledge of different topics which will help you ease into conversations related to any of those topics.

Since I'm really shy my friends don't notice me as much and when I start middle school I want to start new, like suddenly after two months I'm actually not shy anymore. But I'm not sure how do that and what if I leave them will they tell all my secrets. So I need help and fast.
You sound a lot like me when I was your age. I was also very shy. I always said that I was going to be as outgoing at school as I was at home. Eventually I did, and this is how. I realized that my opinions mattered just as much as everyone else's. Therefore, my opinions needed to be shared. Don't try to be excessively outgoing to the point that it feels uncomfortable for you and those around you. It's OK to step out of your comfort zone, in fact it's a good thing, but if you try to force it or fake it, It will be weird for you and those around you. In other words don't try to hard. Let it come naturally, for lack of a better word. The important thing is that you don't change who you are. You need to not lose the characteristics that make you you, but you should step out and let people see you. If you hide from them, then they are missing out on the pleasure of knowing you. Just keep in mind, you matter just as much as the rest of them. Don't let anyone intimidate you. Go out there, be yourself, and be proud of who you are. Don't let anyone try to make you shy away from the crowd. If your group is having a conversation, put your 2 cents in. If you're all standing around wondering what to do today, don't just go with what everyone else says do, put your opinion in to. Find simple situations in which to be assertive, and you'll find it comes easier and easier. Hope this helps. Good luck:)