He would always tell me "you're making problems that aren't there. Relax. I love you. I'm with you for life". Above anything else, it makes me feel like I was lied to.

This comment right here tells me that there's so much about your ex and you that is incompatible on a very basic level. He's just not open and verbal enough for you in the relationship: some people are like that, but that doesn't mean that you have to twist and turn yourself into a pretzel trying to be ok with the crumbs he's giving. I do feel like he is processing everything internally and not letting you in on things, and then kind of penalizing you for needing more information from him.

Bottom line is that I definitely think that you should focus on yourself no matter what and let this guy GO for now...don't call him, don't beg, don't tell him you miss him, don't try to "help" him in any way...just go do your life. Frankly this guy's jerking you around. Maybe not deliberately, but does that really matter? You don't deserve to have to wait until he FEELS LIKE including you in his thoughts / inner world. And you also don't have to feel like you are somehow WRONG for needing more communication than he gives you.

I dont' know what happened but sometimes you don't know this stuff until way later. Let this guy figure out his shit, and if he comes back and wants to tell you what was going on, MAYBE you'll be open to that, MAYBE you'll have gotten past your hurt enough to not really want to deal with someone who treated you that way. I know it sucks but you have to do this.