Friend problems!

 I have two friends lets call one S and one M. S is a girlygirl and M is inbetween a girlygirl and a tom boy like me. Well i like to hang out more with M. We always hang out and play sports and get sweaty and hot. S is not like that. Also whenever M and i talk about what we did S gets mad. I only see S in school but i see M in and out of school. Also S is always giving me atittude then says that i give her atittude. So i dont really like her that much. Also M might go to my middle school.(were in 5th grade.) So ill always see her but not S. S always just walks away with her mom after school but M walks with me sometimes. So how do i kind of stop being her friend and hang out with M but not S feelings. Also im scared that she will tell everyone who i like. Thanks. Please Please Please Please help me. Also i dont want to stop being s friend completley.
` a concerened friend

Dear a concerned friend,
There is really no nice way to tell someone that you no longer want to be their friend.
Lets look at this as if this was you. If you were S and you were hearing about what M and you did to which you were not invited to, you would probably feel left out. It seems to me that your friend S doesn't have a lot of friends. She walks home with her mom after school, maybe she is shy to making friends too. You and M seem like great friends, but S seems like she just wants to be invited to hang out with you and M. Just because M is more your type doesn't mean that S can't come along too. If S is a girly girl, she might still like to play games like that. You are all only in 5th grade, things can change. I would wait it out until you all go to middle school because S isn't going with you, so eventually when that happens S will be at a different school making different friends and you and M will be making new friends as well. Telling S that you don't want to be friends though could lower her confidence, and hurt her feelings, so I would wait until you change schools. Good luck!
-Jenna