I'll try to write this out in a way that makes sense, ah. Sorry for the length but I feel I need to give as much backstory as I can to this.
I'll preface this by saying I have diagnosed mental issues (won't specify past they're behavioural for privacy) and they affect my behaviour at times. My ex also has diagnosed mental issues, but not the same as mine. 
We were together for about a year or so, where a lot of things happened to us both, making us both quite unstable. We were both severely dependent on each other and sacrificed a lot of time just to be with each other in fear the other would kill themselves or worse would happen if we weren't with each other. They broke up with me a few months ago, saying they couldn't handle my instability on top of their own and their own life ect, which I can't blame them for at all. I'd have a lot of breakdowns in which they'd be afraid for my safety, to the point they'd not go outside or focus on school as much as they should do. I want to stress I NEVER asked them to do this, it was never me telling them to drop everything and comfort me. They did so without telling me how badly it was affecting them and I was somehow unaware they were sacrificing so much. I did the same as well, admittedly, us doing this fucked us both up even more, and I think it was a massive contributor. Neither of us wanted to admit anything was wrong or break up at the time. Them keeping things from me, even incredibly important thing was a long trend as well. I knew them well enough to tell they were hiding things, but they'd insist nothing was wrong. 
To the proper point of this, after the breakup and enough time for me to be calm about it and be able to speak to them and be alright, they told me they still wanted to be friends, which I was fine with, saying how they wanted to travel with me in the future, planning all sorts of things, ect. When they're not making all these sorts of promises they're completely ignoring me even when I'm asking them about very important things, which I don't take very well to from anyone. This pisses me off, because I feel like I'm being thrown around and played with.
I've asked my close friends about it, but I neglected to mention how I also felt messed up from the relationship. I feel like I've been an asshole and that its all my fault, but my friends for some reason tell me I'm not. Either its obvious I got messed up too from how toxic it ended up being or god knows what.
Sorry for this mess of a post, rip