I know how you feel, i have been in the same place where you are at now,
you may be in love with him and thats what it sounds like, but he may not be in love with you. you should just accept that and move on, i know its hard to just have him push you aside and then act like every thing is ok and that he didnt do anything worng to hurt you, but he did and if he does it once he'll do it again and he proved that, this guy you love sounds alot like my dad, i know that sounds funny but my dad did the same thing to my mom as this guy is doing to you, and even after 20 years of not beeing with my dad my mom still admits that she loves him, and i, like i said, have been in the same old game that you and him are playin now, its been 2 years that have gone by with out beeing with the guy that i thought was the one for me and i still cry at night because i still love him but he dosent love me back. i figured that he was the one for me but i wasnt the one for him. and i guess that is also true in your case, trust me it will be hard and it will be a lonly trip until you relize that you desreve better then someone who is never there, and just think if he does this to you now, what would happen if he had your baby? im sure you wouldnt want to put your child trough that too. but one day you will find some one who loves you and wants to be there and is there.......your only 18 you still have a lot of life to live and a lot of chances to met the real man of your dreams, dont settle for some one who cant even take of him self, and if he is taking ANY kind of drugs then he is not taking care of him self.....hope i helped