Relationship has ended????

Hello all, I need some advice on this topic as I'm so heartbroken, sad, and very confused.  I was dating this lovely guy for about 5 months who has ADD. I didn't know he even had ADD until 3.5 months into the relationship where he dropped his Ritalin pill on the ground and I asked what it was.  We were doing a long distance relationship and things were great.  There were some quirks about him that I have now realized where ADD like behavior.  For example, he has road rage and drives like he is in a hurry all the time.  He tends to get offended easily if he takes what is said to him in the wrong context.  He never admits that he is wrong about anything.  He told me that during xmas break, he went back home to visit his family and cut his short trip b/c him and his grandma got into an argument and rather than stay there the last night, he lied and said his flight was a day early and decided to stay at a hotel instead b/c he couldn't handle the situation.  Well, I went to go visit him for Valentine's day weekend. He had to work both Saturday and Sunday b/c his team had a deadline to meet and work was insane.  Prior to Valentine's day weekend,  I hardly heard from him.  Texts were far and few.  I gave him his space as I knew he was stressed out.  Valentine's day weekend was fine.  I didn't expect anything nor did we do anything. I didn't care.  He kept telling me how stressed and exhausted he was and that he's not sleeping well either.  The last evening we spend together which was Sunday the day after V-day, we were getting ready for bed and he didn't want to be intimate.  I felt rejected and was taken aback b/c he's never rejected me.  He simply said he was too tired.  I immediately got defensive b/c it felt weird, considering we are doing long distance.  My guard went up thinking that maybe he was no longer interested in me.  I tried to talk about it with him and that went no where. Unfortunately, I brought up the fact that I never hear from him anymore and that I was feeling neglected.  Low and behold did I then realize that he felt attacked by my blaming him.   He immediately got defensive himself and we started arguing.  He got so mad that he started cursing and yelling at me and we both went to bed upset. The next morning he dropped me off at the airport.  The car ride was in silence.  He did give me a hug and unfortunately I wasn't very receptive, which I wish I would have been.  After he left, I sat at the airport and started googling ADD and relationships.  I began to realize that I wasn't understanding him when he said he was tired and stressed and instead was placing my needs before his, thus causing him more stress.  It was clear as day that he doesn't do well in stressful environments.  Well....needless to say I did reach out to him and apologized for everything and he wasn't that receptive, which I wasn't surprised by any means.  He, himself, never apologized for cursing and yelling, but I didn't expect him to.  Days would go by and I would text him pretty much every other day to see how he was doing.  He would respond short texts most of the time, but never asked me how I was doing.  One day, I guess he got irritated with me and told me he didn't have time to text.  I left him alone for a few days and reached out to him again.  He, again, wasn't being responsive.  Finally, I reached out to him asking to talk and he refused to.  I then proceeded to ask why and he just basically told me to leave him alone.  I told him that I wanted to spend some quality time with him as I  wanted to work on repairing our relationship and how I thought it was worth saving.  He said he was no longer interested.  I didn't get a real reason why he wanted to break up other than he telling me that I consistently ask him if he's seeing some else (I've only asked twice and that was since last time we visited, anytime prior I have never asked.)  I told him that we had a fight and it was just a huge misunderstanding.  He wouldn't really text back.  I asked him if he loved me and he refused to answer the question.  He said he wasn't going to answer any "loaded questions."  Two days later, I reached out to him again asking to talk and he said "no thank you."  He refused to talk about what had happened. I told him that I thought he was being unfair to me and he said he didn't care.  The texting ended pretty badly with me asking him if he honestly didn't love me and he said, "not like that anymore."  So I ended the texts by kindly thanking him for everything and to take care.  He says, "you too."  I'm crushed!  He was very affectionated and loving up until that last night which I totally took the wrong way.  But, why is he so upset and bitter?  Is this typical ADD behavior?  And if so, if there a chance that maybe he might come to his senses and realize that he made a mistake?  I don't understand how he could change his feelings so quickly and want to break up.  I keep thinking that he's upset and rather than deal with the issue, he'd rather give up, thus the break up.  I'm really heartbroken and even more confused.  Any advice.  We haven't texted for 5 days now.  I doubt he will reach out to me.  Should I accept that this is really over, or is there still a chance?  Please help!!!!!!!