What do I do if he won't let me leave ?

My bf and I have been dating for ten months now ... I feel like I'm losing my feelings for him bc hes far from me now. but he doesn't accept that! I like someone else too.... But my bf thinks I like him bc I don't see him much and it's just that I'm missing him... I don't want to hurt him but. I feel like if we don't break up soon I will end up cheating on him and I don't want too but wth can I do if he won't let me go he makes it so hard on me he says that if I leave him he'll be a manwhore and wouldn't care bout himself all bc he wouldn't think that love isn't real. What do I do.... I can't live like this I feel like I wana be single and have fun then be in a relationship when I want to be serious about it it's just that... He thinks I'm going to leave him for the guy I like It's not like that I feel that im still young and I just want to have fun! I'm not ready to devote my whole friggin life to someone yet! And i wont leave him to go out with the other bc i do want to be single dk... This cannot go any longer I talked to my mom but she says that I should give it time to think about how I really feel ... I do like the kid I cannot picture myself having any one elses kids but him the thing is I feel that I'm too young to make up my mind now . Belive me I told him about this but he still makes it hard for me...