He let me down

I started seeing this guy for about 3 months and everything went well, he would treat me right, text me all day and everyday. He was just the sweetest we would talk about a lot of things. Until a few weeks ago when his ex found me on IG and started to text me. I would screenshot and show it to him and he would tell me to ignore it. He tells me the history between them. I get it, he was really in love with her but they were exes for a reason. We would talk over the phone and all because he worked away. He keeps telling me there’s nothing to worry about. Between him and his ex are done. They’re over. He would tell me over the phone that she would tell him that she’s coming to town to be with him and all this over bs. A few days ago he started to act really strange with just opening my Snapchats and leaving my messages on read. So then I asked him” hey is everything okay, did I do something to you? Talk to me”

...Nothing.. he continues to leave me on seen. It went from him all lovey with me to complete strangers in days. I went to send him a snap but realised he deleted me off everything. Without saying why, or what. I’m so pissed off. I’m annoyed, I feel so hurt. I feel so heartbroken. I feel used. There’s a part of me thinking he’s back with his Ex cos of the “history” 😭

I’ve been distracting myself so bad but it’s still in the back of my mind. Can I please have some advice. Please no negative comment xx.