Relationship with a 25 year old that has ADD

I'm 32 and dating a 25 year old male with ADD/ADHD.  I have never experienced a relationship like this, soo hard to be with someone who has this disorder.  He was diagnosed young and is prescribed medication but does not take it.  In the beginning there was just something about him that was great....there still is.  To me he's different and theres just something there. We moved really fast in the beginning, started dating and then he proposed. I was once married and with someone for 13 years and it ended badly so since then I've had walls up about dating and guys in general but again with him there was just something different.  I told him yes but the agreement was we were not going to set a date, that marriage would be in the future.  Ots now been almost 2 years and more then not the relationship is horrible. I read all the posts and it's exactly what's happening with me/us except he has major issues with thinking I'm cheating or talking to other guys. He has said the most hurtful things to me. I feel exhausted of the situation, I dont know what to do anymore. I feel like he knows nothing, like he was never taught this a ADD thing? He seen a therapist a couple times and that was it.....recently got diagnosed with depression and is now taking medication for that.  I feel like his insecurities will never stop, always making rude comments.  I have never given him a reason to think I'm doing something behind his back. He was cheated on in a past relationship but it's a constant ordeal. Im kinda lost on what to do....I love him and want this to work because again there is just something about him....he can be so great! He states there is nothing wrong with him and that him going to therapy and getting on depression meds is for me.  Always mt fault.  Any insight......advice..anything! Am I wasting my time? Can or will it ever get better?