EX BOYFRIEND, PROM, NASTY TEXTS, TEXT TO HIS EX CALLING MY FRIENDS AND I DESPERATE? wtf help me & state your..?

my ex and i were back talking and exclusive, not going out but only seeing each other.. i read a text message on his phone to his ex ( the reason we broke up & had many fights over her ) that read " please come to this party at the beach other wise they are going to invite the desperate junior girls.. please come" .. i was under the influence and he denies writing that, he said his friend made him (he named the friend ) because he was being desperate and wanted the senior group of girls to go so he had him write it because his ex would want to go and get them to come... would you forgive him for this ? i gave him a hard time and he tried his best to get me to forgive him. he tells me he still loves me, and a day b4 that he sent me flowers, made me a romantic candle lit dinner and asked me to prom on valentines day. threes got to come a point in time where you tell yourself to let go.. am i right? now he is trying to turn this around and say i don't believe him and im mean and *****. i last night brought up a subject of prom because 3 other people are planning to ask me, and i want to know if were still going together but he started saying i want to .. i think, its hard to tell right now.. does he really want to go with me, and is he just mad because other guys are on his territory?