When to call it quits with ADHD partner :(

I just came across this community and felt like it might be helpful to share my story / current situation.  I've been in a 6.5 year relationship with a VERY ADHD partner.  We were best friends for almost 10 years before we started dating (since high school)....we have a lot of the same interests, he makes me laugh, is fun, smart, hardworking, and one of my favorite people.  However, the relationship has literally never been easy.  I feel like we have had to work so hard at it and it's honestly just exhausted me [beyond repair, I'm worried].  I feel like I'm the one who has had to make all the sacrifices and give up my needs.  And it just feels so unbalanced.  I feel unloved, unseen, neglected, taken for granted, and often feel like I need to behave in a parent capacity (which is really unsexy / a huge turnoff for me).  We have sex, but there's literally no romance outside of that. And it hurts me that he shows up very differently for his circles than he does for mine....i.e. he can turn on for his coworkers/friends, but does not show up in the same way for mine if he's not in the mood (which is often)....yet I always show up with energy for him & his circles.

He is constantly distracted, gets absolutely absorbed in his phone, never asks me about my life (even though I constantly ask him with questions), can be very moody in a way that really affects me and brings me down (zero emotional boundaries), can't compartmentalize, and very volatile emotions.  We did therapy for a year, have had countless conversations, and written letters expressing my needs - but I feel like nothing ever changes....at least not long term.  

I know he's a good person & I know the problems in our relationship stem from a mental illness, but I also have needs (and suffer from anxiety/am pretty sure I have a little ADHD as well, just not as much) and I just don't know that I'm the right partner for someone like him who naturally needs more in the relationship.  I am very independent, but deep down I've also realized that I crave a partner who can take care of me, support me, and make me feel special....and so far he's really fallen short here.  I know I would have ended this relationship years ago if we hadn't already been good friends for so long....but even with that foundation, I'm not sure it's enough.  I love him...but in the process I feel I haven't been showing myself self-love.

I told him I thought we should break up, and he acted like he was in total shock [which really goes to show how little he pays attention to me since I've majorly depressed over this relationship for a couple weeks].  He wrote me a letter expressing how he was going to start trying harder to make me feel loved and taken care of....but I just don't think I can trust him.

Anyways, I don't really have specific questions....but if anyone has been through anything similar or can offer any words of advice, I'd really appreciate it.  This is definitely one of the hardest things I've ever had to come to terms with.