Relationship Issues/Breakup

So I'm 20 & my ex is 19... 3 weeks ago on Feb. 22 he packed his stuff & left my house. There was this girl who was his "best friend" since high school before we even got together & I seen her once in awhile never had issues with her bc we are a lot alike. Well recently she had been posting pictures on instagram & fb of her & him that said stuff along the lines of I love you & no matter how long we go without seeing each other we can always pick up where we left off. It kind of bothered me but I didn't say anything until 3 weeks ago when a twitter post was made about how my bf infuriates her trying to help make decisions. So of course I texted him like what is that about & he's like oh she wants to hang out & I simply don't know what we should do. I said ok but were you even going to tell me? Was I included? And this girl has always been very flirty with him & thats what had me so worried even though they are friends. He's said I 100% don't have feelings for her & she doesn't have feelings for me. I left it go & another stupid argument arose from this situation which lead him to come take his stuff. 
He called me after he got back to his house & begged me to take off work to come talk this out bc our relationship is more important..I did & basically he said that he needed space & time to himself & gave me a long list of all these things that I have been doing that I need to fix. I agreed to work on it & seek help from his mom who is a dr. In psychology & go see a therapist. We BOTH agreed we were working this out. He hugged me & kissed me & said I love you then walked me out to my car & did the same thing. 
We texted normally the next 2 days, when Friday came around I was like we need to talk in person again bc I felt like he was shutting me out. We went to dinner & he told me how he can't just go date someone else bc we have been together for 2 years & made so many memories together. He also had given me a beautiful promise ring that means so much to me last March so I wasn't giving up that easily. On the car ride home I explained why I do some of the things I do some of them have resulted from a broken home & I don't know any different. I broke down & he rubbed my leg the whole way home bc I NEVER cry like that in front of him & he always got so worried. I slept over that night..we cuddled, kissed, hugged, the whole 9 yards I was in my happy place. He got up for work in the morning hugged & kissed me & said see you Monday.
He is an EMT so he did 2 days of work straight but by Sunday he said we should take a break. I freaked out bc I was scared that if we did he wouldn't come back. He said we just need to take some time for ourselves then we can re evaluate us. He said I was making more progress in the past 2 days then in 2 years & if I continued he would certainly be right back with me. By Tuesday we have school together I figured I shouldn't sit with him like usual so I didn't & he texted me "you aren't going to sit with me now?" So I walked over & sat with him it was like nothing was wrong. 
The next day we barely talked so I just simply sent how I was feeling about our situation & told him how he wasn't showing me any emotions about this which he was the most sensitive & emotional guy I've met so it was odd. He just completely snapped on me & said he was done with me & he couldn't lie to me or himself anymore. I texted his mom & we talked the next day about everything & she said just give him time he's just immature & hasn't processed this situation yet. I texted him that I met with his mom & he said that's great but as of now I don't want us I just want to be free. 
We didn't talk until Monday when I initiated the conversation just asked how he's been & all. He answered me back sweet as can be like normal the next 2 days until Wed. I just wanted to talk in person so I asked to call him & he said it needs to be at 9:30 & quick so I'm like ok thats fine. Well he called & said how he can't say he loves me anymore & it's nice to not have to answer to anybody & I tore him down for 2 years & he doesn't know if he can put himself back out there. I was hurt & it didn't help he was yelling the whole time I thought we agreed to working on us & its like now everything got changed suddenly. He hung up & 45 minutes later texted saying "so sorry for being mean I've just been edgy lately & you have just got me at the wrong time" 
His fire company banquet was this past Saturday which he had initially invited me to well he had taken his "best friend" I was upset & shocked he posted her on instagram & said my beautiful date & made them his profile picture on fb. Well Sunday he texted me completely random "im glad you lied to me" like I can't figure out why he's trying to pick fights with me or even talk to me. Then my friend posted a not so nice comment on his pic which I had no idea she was going to do & he sent me a screenshot of it & said to get my f'ing friends under control or he would address this himself. I never answered both of his texts.
But he texted my friend & said that he wasn't in the wrong here & can't help that he moved on since I treated him like absolute shit. And told her to keep her mouth shut then blocked me & her off his fb. My friends bf then messaged him for disrespecting his gf & how he's a caring friend of mine & does not appreciate the way my ex has been treating me. My ex said that I never allowed him to hang out with this girl & how I always accused him of having a crush on her but the fact of the matter he didn't & all this bs...makes NO sense. 
This past Monday we got snow & his "best friend" & a bunch of other people had stayed the night at the firehouse to run calls but I never was invited to do that stuff because Im not a member that can run calls so why was she? She hasn't changed her pictures to them 2 yet nor have they announced they are a couple but its like wtf?
 I am head over heels for this kid, he gave me the world, helped me out when I needed something, bought me everything I wanted but didn't need, & I thought this would be my last relationship considering he kind of committed to me & the way he gave me my ring was his "best friends idea" but now he completely flipped. My parents seem to think he's playing games with me to piss me off but Im not so sure? I'm lost...he just shut me out & never gave me a chance to prove change. He just said I pushed him away & he gave up then? I gave him the time & space he asked for & still tried to communicate (which we both agreed to still do) but he shut me out...