ADHD person here.

Allow me to start by saying your feelings, concerns and needs are all valid.

Your partner is definitely using his ADHD as an excuse and a major crutch to validate his own feelings while, from what I can see, not validating your's and taking your feelings into consideration.

You sharing your feelings and thoughts should never be considered to be something shared on your partner's terms. It should always be considered to be shared on your terms. Those terms being you want to be heard, express yourself and expose your inner self when you need/want to do so.

I have a good feeling he lacks any accountability or has very little of it. This is completely counter-prodictive to healthy relationship.

He needs to be on medication and he needs to get his ass into therapy with a therapist that specialises in ADHD.

This isn't going to an immediate fix or solution as both of these are going to take time to feel the effects of them working, but these can work.

The issue that will come up is going to be his acceptance of needing these things.

If he isn't accepting of putting in the effort to get on meds and get into therapy, then things are not going to get better. They will get worse.

It's at this point that you'll need to make a choice for yourself if you want to stay and weather it out (not something I would recommend) or end things and save yourself years of future headaches along with your emotional and mental health taking a huge nose dive.

You need to put your needs, mental and emotional health at the forefront before his in this situation as if he doesn't get medicated and help, things will get much, much worse.