Help? Should I text him?

[Emm]

Kinda long I guess lol
I used to talk to this guy. He was a senior at the time and I was a freshman.... Don't judge please. We were talking for about 3 months. Then one day he told me he liked me and couldn't wait to see me again(He lives 2 hours away, met 3 times.) then I got on Facebook later that day. Turns out he got a girlfriend 3 hours after he told me that he liked me.... I removed as a friend. We didn't talk until about 2 months later. He Texted me and I was stupid enough to believe that he actually wanted to talk to me again. Him and his girlfriend broke up. I talked to him until may. Then he all of a sudden he just stops texting me. I was going through twitter and saw one of his tweets about his new girlfriend. Then I saw another one about how he is leaving for the army on September 4th... Which is tomorrow. I thought I had deleted his number but I was going through recent calls and his number was still there. Should I text him and tell him goodbye or just leave it be. I don't want him to think that I'm obsessed with him if I do text him. And I'm scared he completely forgot about me. That'd be embarrassing... But I also don't want him to think that I never cared....
Ps: I'm a sophomore now and he just graduated.....