Loving someone who hurts you?

I have this friend, that I honestly love to death. I don't have many friends, and when I'm with him I have so much fun, and I just love talking to him and being around him. But when he gets around his other friends he is so much different. He hardly talks to me, and when he does sometimes he treats me like I'm stupid.. It's almost like he's showing off and acting like he's too good for me. But when it's just us he tells me he loves me so much and that I'm his best friend. A while back his cousin and I didn't like eachother and he spent the night at her house one night and called me and told me he didn't want to be friends, and told me that he was too good for me while they were all ganging up on me and laughing in the background. He also told me that his cousins friend was way prettier than me and that she was going to steal the guy I liked from me. And then he tried to call me that night and apologize, but I was too hurt to even hear his voice. I cried about all of this forever. Its still painful to think about because I trusted and loved him with everything that I had and he turned on me and acted like I meant nothing to him.. Eventually after about 2 months of not talking at all he called me and gave me a sincere apology and I forgave him because I missed him so much. Anyways every time he hangs out with his other friends I am terrified that he is going to decide to do that again, so I try to be the absolute best friend I can be.. I even apologized to his cousin that didn't like me, even though I didnt owe her one. I am so confused.. Am I only hurting myself by sticking around and will he only do it again? Or am i safe sticking around..?