After 1 1/2 years with my boyfriend, we are still having issues with him texting/facebooking other girls, I need other opinions on the matter

Hey guys. So my bf and I have been together for a yea and half, I've waiting for him through 3 months of boot camp, combat training, and him having to move away to fulfill his military obligations. Just before he left for boot, about a year ago now, this girl was calling him in the middle of the night, texting him nonstop, posting stupid stuff on his Facebook (I despise fb, by the way), and just approaching him in ways she shouldn't considering he's not single. I asked him to have her back off, yet behind my back they were messaging on fb, texting behind my back. Then, while he was in boot, she would post things on his fb saying she had dreams about him, how she misses him, etc. Then invites herself to his graduation. Thankfully his family took care of it. But even now, a year and a half into it I still catch them texting and finally had him delete her number and his fb (he's talking to another girl "friend" simultaneously behind my back, shit talking on me i might add, inviting her to visit him behind my back, etc.). I've just had enough with this distrust. My questions are: am I being a psycho gf for wanting him to drop her as a friend? Should I really be threatened? And is he in the wrong or am I just being nuts?