Hmmm friend who has a gf keeps asking to have with me?

k well we were talking for a while about hooking up and then once skool started he started to talk to this freshman and now they r going out. this girl is on my volleyball team and i see her for atleast 4 hours a day at practice. so now that they r going out he still IMs me and Texts and calls all the time. he sends me dumb little messages like "i love u" and stuff and i think its just to see wut im going to say to it but now hes starting to ask if i would sleep with him or if he can come over and wed go to the golf course so our golf cart can "break down" whichfrom b4 i knew meant have . so ya i always tell him that we cant hook up cuz hes has a gf but he still tries to push the issue. should i tell her wut hes doing. if so should i show her the IMs so she sees what he is actually saying and maybe shell believe me. cuz my friend told her anonomysly b4 to watch out cuz hes a player but she didnt believe her. whats should i do?