I am going to be blunt. Who cares why he did it? The guy is a jerk and you are better off without him. I don't deny your feelings for him, but you know in your heart he is not right for you. Just give yourself time to heal and discover who you truly are. Once you do that, you will find someone who will treat you right, and one that won't make you question their motives.
All sorts of red flags in your comment.
Relationships are habituating--- whether good or bad---so feeling sick to your stomach thinking about him with someone else is quite normal.
If I were you, I would require him to give you some space and concentrate on getting his own head out of his own rectum.
Block him on instagram and get on with your life, he's a gameplayer. You've said yourself that you shouldn't of put up with it as long as you did, even if you ignore our advice at least take your own. Given time and hanging out with your girl friends you'll be glad you got him out of your life.
I stopped talking to my ex boyfriend a few days ago. He treated me like crap and only showed he cared about me when he knew he was going to lose me. He told me I was paranoid, annoying & "it was just in my head"try to talk to him about how i feel. Its all wrong. I shouldnt of dealt with it for as long as i did. Im not paranoid. It was really happening. However, i would I texted him the other night asking how he could just let us die off so easily and all he could say was how I was the one who stopped talking to him. I said i needed space because I couldn't deal with the constant cycle of being upset all the time and only ever happy when he would actually show me he cared. Yesterday I went hiking with my friends and he texted me. I told him to leave me alone to which he said " Have fun with the other guys you're talking too" all i said was okay and he asked why i didn't deny it. I just simply said that what i do is no longer his business and that i wanted him to leave me alone. He never answered. 2 of my friends posted a picture with me that same night and he liked both of them plus the one i posted. Then i saw that he followed another girl on Instagram, so like any girl would, i just checked out her profile. His changed his bio on Instagram to match exactly like the girls he followed. Down to the last space and period. All it says is their age and then snapchat username. As crazy as im about to sound, i know what it looked like yesterday morning. So i knew when he changed it. He made it look exactly like hers, just with his information. I dont know what to think of it. I need space from him and if things are going to work out they will eventually. I just dont understand why he changed his bio. Is he trying to just make me mad like i think he is or is he really talking to this girl? I know i need to stop looking. I know that i need to let go and move on, for now at least. I dont text him anymore. Im done asking questions. If he cares he'll prove it to me. But as of right now i deserve my own time to do my own thing and figure out what i want. I just dont know what to think of this whole thing with the other girl. Maybe im just overthinking it. Im just confused and still so in love with him that the thought of him with some other girl makes me sick to my stomach.