So what should I do about it?

so theres this gut that my best friends used to go out with (dont currnenlty go out) and we talked like a little but now my best friend hasnt been in cl for something and so he strted talking to me more often and we just talk. he tells me about some girl that talks to him and flirts with him, he says shes a freak, and we just tslked about random stuff,and i started liking him. and lately when we re talking he has been very physically close to me, i dont mind its just that when im not talking to him hes doing the same stuff to another girl. and its getting on my nerves. i wil not talk to him, he will think im like a stalker. and i dont really know about dating him because my best friend still has feelings for him... but shes not aroundd anymoree... ;) so should i just stop trying or do something about it?