I need to get over him?

Me and my boyfriend were going out for 4 months, before he left to go to the other side of the world for 9 months, we both knew he was going well before we started our relationship, and agreed to stay together while he was gone. After 2 months of being out there, he broke up with me, saying he felt he was holding me back from my life, and that he wanted me to live my life not waiting for him because his life is always going to involve travelling and being abroad, even though we both agreed that we would make it work. He assured me that there was nobody else and that he was only doing it for me, but that i should see it as a break and he'll come and see me when he is back and we'll see if we feel any different, he also asked me to keep wearing the necklace he bought me to remind me of what we had, and can look forward to when he is back. The problem is, this was 3 months ago and i'm still so so so upset about it, i think about him all day everyday, we still email eachother daily (honestly the thought of breaking contact makes me cry), i still obsess over his facebook and get jealous of pictures posted and comments made. I just want to be okay with it :( it's tearing me apart.