I'm exhausted and don't know what to do. Please seeking advice and guidance. Apologies for the lengthy post. 

Me (28 y/o F) and my fiance (29 y/o M) have been together since about 2015 and got engaged in Summer 2022.   He has an ADHD diagnosis since he was a child.  Currently un-medicated.  As of 2021 he has discussed his feelings of depression and anxiety with me. (I've encouraged therapy and professional help on multiple occasions but he refuses).  Since getting engaged we're not getting along and I feel like I'm losing my sanity. 

For background, trying to summarize as best I can -- After getting engaged last summer he went on a bender of drinking alcohol and smoking marijuana beginning all day every day for about 2 weeks. He'd previously been a weed smoker for years but not to this level of abuse.  I expressed my concern a few times.  He only stopped once we had an enormous fight about it. He admitted afterwards that he uses marijuana as a crutch to deal with his emotions.  He said he was experiencing a lot of emotional difficulty at getting engaged because it was such a big life change, his childhood is over, etc.  Due to this, I suggested we try couples therapy.  I wanted to work through his substance abuse, depression, etc. with him in therapy.  We went a few times but he refused to continue and said "we need to learn to deal with conflict ourselves." I, of course, felt awful.  Being newly engaged, this was supposed to be a very happy time and it wasn't. It seemed like couples therapy gave him license to turn his substance abuse and mental health issues on me and make them my fault.  He would say "you're the reason I'm depressed", "it takes two to end up in therapy", etc. 

Since that time, for about a year, we've continued to have issues.  The issues have escalated and I need help, I'm at my wits end.  He is extremely difficult to talk to.  I feel like I'm losing my sanity.  Every time we argue I feel smaller and smaller.  I feel like I'm living inside a vacuum and when I step away from him I'm like oh ... "wait a minute, I remember who I am."  I feel like I don't know what a normal argument is anymore and what I am allowed to be upset about.  Whenever I'm upset I feel like he flips it on me and somehow I always end up apologizing when I was the one who went into the discussion feeling upset!  In arguments if I say "when you did X, it made me feel Y" he always replies with "you are accountable for your own emotions. I am not responsible for how you feel." Or "I can't help the way you feel, you need to control your own emotions".  We can never have discussions about hurt feelings where I say I was hurt, and he simply apologizes for being hurtful.  He always has a convenient way to make it my fault.  I am tense around him because I don't know what his mood will be or how he will reply.  He flips angrily and becomes paranoid and the simplest things.  I find myself agreeing with his logic just to stop the argument and come to a peaceful place. 

He is either extremely disciplined, or not.  Which I believe is characteristic of ADHD people.  And when he is disciplined, he is extremely arrogant about it and lords it over me.  Constantly telling me that I am not accountable enough and need to be more like him.  I am constantly not doing something right in his opinion and he is constantly critiquing me.  When I bring up that his critiques wear on me he tells me to stop playing the victim and be accountable.  He rarely asks questions of my activities and just tells me what he would do.  When I disagree, he tells me that I don't listen to him. 

Recently, I put on a pair of gold hoop earrings to go to dinner with him.  He told me he didn't like them and wanted me to take them off.  I told him I liked them and wanted to wear them anyway.  He asked me, why wouldn't I want to dress in a way that is attractive to him and said that it is disrespectful to him (as my fiance) to go against what he finds attractive.  I said I did not ask for his opinion and asked him to respect my wishes.  He said "why would I ever compliment you again if you don't listen to me when I'm telling you now I don't like something."  I get so stunned at how such a simple thing escalated into an arguments. It is making me feel crazy because he always finds a way to manipulate the argument into a way where he is right.  I have had dozens of arguments like this.  I cant even remember them all anymore.

I lost it today and am strongly considering calling off the wedding.  I can't take much more.  He is involved with coaching after his regular 9-5 job.  I was leaving for work this morning and making polite conversation when I asked him "if he had practice tonight?"  He suddenly became irate. He started angrily repeating the question and following after me yelling "Do I have practice tonight?!  Answer the question yourself!  Do I?!"  I was so stunned and replied that I wasn't sure of his schedule because he hadn't given it to me.  Over the weekend his dad shared the schedule with me and I forgot that I had it.  My fiance continued to stomp after me yelling "You're asking a stupid question!  My dad gave you the schedule!  Stop being a liar!" I walked out.

I was stunned at how quickly the situation escalated and sat in my car before work to reflect on the situation.  I wondered, as we approach getting married, that if I had a child with this man and he spoke to me in that manner in front of our child, would I be proud?  Would that be appropriate?  Would that be something I'd want the child to witness? No.

I texted him this morning from my car saying "No one deserves to be spoken to the way you just spoke to me."  He texted me "Stop playing the victim." He can just never apologize for his behavior.  I get it that I had the schedule but I really don't feel my question warranted that response.

I feel like I cant have a conversation with him anymore.  I don't know if its NPD or ADHD related but I am emotionally drained and stuck.  I love him very much and that is why I struggle with what to do.  It is difficult to consider ending things with someone you love but I feel like he isn't the same person anymore.  These arguments seem incredibly abnormal.  Do people who have been together almost a decade just have these issues?  Please help. 

EDIT -- I want to profusely thank everyone who has taken the time to weigh in and help a stranger in a time of need.  Your thoughts are appreciated and have been very helpful in sifting through the chaos. 

EDIT (again) -- I ended the engagement and relationship.  It has been personally very difficult but your advice helped provide clarity on something I had been struggling with for a while.  Thank you.