Is it ADHD or is he just a jerk?

Ive been reading all your posts like crazy today and have to admit it feels so good to know Im not alone! So here goes my first post. My fiance and I have been together 4.5 years. Hes known he has ADHD since a kid, was on medicine up until he was teenager, he took him self off as a teenager due to the stigma he says (hes 36 now). Hes the extreme workaholic type, always has to have a project going on, will never just stop moving. Everything is his way and on his time. Although frustrating I appreciate it at times because its get me moving and we've accomplished alot together.

Two days ago we got into a fight. We were working on a outside enclosure for our chickens (a project that seems to be never ending and nothing will go right) everytime we work on this thing he throws what I call tantrums because something wont be straight or because the chicken wire looks wavy. Hes just a nightmare and I become the "punching bag" he snaps at everything little thing I do. I just feel like I cant even breathe right around him. So I stapled something too close to the edge of the post, it was supposed to be like inch over. You would of thought I knocked the whole thing over. He was all "What is wrong with you" "what are you thinking" "why would you do this". I couldn't take it anymore, he does this often and sometimes i just let it go because if I talk back it just be comes a never ending cycle. But this time I said I cant take this anymore you're not speaking to me like this anymore and I started to walk away. Well he lost it even more, threatened to tear the whole thing down all because im being dumb. I told him hes an asshole, so he threw the staple gun (not at me, just off to the side) I started crying and he just said im being ridiculous. I knew he would in fact rip the whole thing down, and theres no point to keep talking because he just gets madder and madder, to him he is never in the wrong. We continued to work, he was back to his normal self acting fine and calm, I just stayed silent. Later he asked why I so mopey, I said because you hurt me when you do that, you talk down to me and just keep putting me down, I cant do anything right with you lately. I said its not right for you to speak to me like that. So (as usual) he goes to extreme defense mode and says how Its my fault, that I messed up, I did something wrong and that if he cant make me happy and if all he does is put me down then he should just leave. Hes never said anything along these lines before so it just completely caught me off guard. he said if i want him to go then he will and he wont fight for me because hes fought for a girl before and it was awful. So now here we are 6 months before our wedding and hes already making it clear he wont try to save our relationship all because I just want him to be nicer to me.

So as usual afterwards he acts like nothings happened and my mind is racing. I told him a week before I wanted to start therapy, for my own issues. Ive struggled with self esteem and weight issues, and given our hectic lives its just getting worse. I feel like im drowning. We have 4 dogs (he breeds and trains german shepherds) hes also a paramedic so we works hectic hours at times. But the dogs and puppies have become my responsibility because hes working and when hes home hes stressed so he finds something else to work on, and its rarely ever the dogs. So their day to day care falls on me. and I work full time too. So the few hours I have when I get home its spent with them making sure they get attention and play time. Its alot and i didn't sign up to be only one taking care of them....and he talks about wanting more! So i told him I wanted to start therapy last week. I had an appointment yesterday, I told him over the phone about the appointment, he lost his mind saying I never told him I was doing it and we needed to discuss it more. He doesnt believe in therapy, which fine Im not trying to drag him to it. So on the phone he just yelling at me saying im keeping secrets and that he should just leave because im miserable and its all his fault and he can do nothing right, etc etc. I tried to tell him over and over it doesnt have anything to do with him I'm trying to fix myself Im trying to learn how to cope with my emotions and just try to be happy. I said all I want from you is too realize how you talk to me and try harder just not do that. He ended the conversation with he should just leave and that we'll figure it when I get home. 

When I got home that night, he was calm and making small talk and he eventually just hugged me and told me he loved me. I asked if he understood now what im trying to say/do. He doesnt, he just kept saying therapy isnt the answer to just go to the gym. And he still sees nothing wrong how he talks me to, its just how it is, If I dont like it then he can leave. I told him I cant be the one you snap at just because your stressed and he just says your the only one there so it just how its going to happen so just deal with it. I told him you have to understand Im always going to stick up for myself when you treat me like that because its wrong. I asked if he wants to postpone the wedding since he had brought up twice about leaving and he said I need to get my shit together and figure out what I want...

So im at a crossroads...im so angry that a big part of me is ready to just tell him to leave (he has no where to go since he would try to take all the dogs and his mother lives with us, we just bought a house a year ago but its technically mine). I know I can be harsh when Im mad and can just cut someone out and the reality would sink in later that it was mistake.

Is the snapping, at times very condescending, inability to express appreciation or ever apologize, self centered attitude the ADHD or is he just a jerk? I want kids...is he going to snap at them and talk down to them? Is he going to give me attitude because I cant help him with yard work because at some point we will have human kids that will need to actually be watched? my mind is going in a million directions...and I just don't know what to do anymore..

Were supposed to be getting married in january, my parents have money into this day for us and Im days away from a hopes of them getting any deposit money back so I feel enormous pressure to decide my life now. Apart of me thinks if theres an excuse for his actions and his inability to consider my feelings maybe i can make it worth....but the other part of me is like why am i the only one who has to compromise and change and he gets jsut tell me to get over it...

thanks for reading my rant...