How can i stop these feeling for my ex?

Ok.. I've been dating this boy for about 10 months now and I love him more than anything. He has told me that when we are both of age he would like to marry me and everything like that..
This is one guy I have had inter course with that hasnt taken...

advantage of me.. and he actually respects if I dont want it.

Well about a year before I started dating him I was with some other kid.. me and him were dating and really liked each other but really didnt communicate or anything so we broke up..

Well I am now in the high school and my ex goes to the same school and my boyfriend doesnt..
I have been spending a lot of time with my ex and kinda falling for him.. I really dont want to because I love my boyfriend so much. me and my ex are good friends now and I dont want to lose him as a friend either...

I dont know what to do... how do I stop these feelings for this ex

You'll stop having feelings for your ex, when you stop hanging around him! One of the quickest ways to get over your ex is to cut them off. You cant possibly be friends with someone you have feelings for. It just doesnt work! Don't talk to them, don't see them, and don't hook up with them. You'll never get over them that way. Think about your bf. Is it fair to him that your heart is still with your ex?

Oh trust me... I know the feeling 2x over. (Except on the dude's side) You just grow to ignore it, or force yourself to seem to have feelings with everyone else too, and then force yourself to have different feelings about current companions. Painful sounding? YES... actually it's not. It toughens you up for emotional issues aswell.