Recently diagnosed partner struggling and avoiding me

I am new to this community but super grateful to have people to turn to to ask for help and opinions. My partner 24M and I 23F have been together for 5 years now, and last week J (my partner) has been diagnosed with ADHD I'm assuming during his last therapy session. After his therapy sessions he always calls me on the drive home to tell me about it. After the session and we do our scheduled call he goes on to tell me that we needed a break from our relationship, to have more space to work on himself, and hung up before I could've asked what happened. (At this time he hasn't told me about his diagnosis. )

After work I came home to ask him what was going on and he seemed to avoid every question I asked, leading me to stay the night elsewhere to give him space. The next day I came home after work and he packed enough clothes to last him a week and went to stay with his mother. The only text he gave me just reinstated the fact that this was on him and that he needs to do this for him and that he still loves and cares for me. I assumed this was him struggling with the stress of his law school finals so I was okay with leaving him with some space. But 24 hours turned into days which turned to a week now. He blocked my number after I've tried to call him on numerous occasions, I have anxiety and abandonment issues so I've been struggling with him leaving so suddenly. 

Knowing that he would return eventually home to grab more clothes I on instinct wrote him a short letter just saying how much I love and support him even from the longest distance,  and how proud I was for him to be finishing the semester. 

Its been a week now..

He came by the house while I was gone at work yesterday and left a note by our bed which summarized as, " I know how hard this has been for you, this has been so difficult for me, I care for you and pickles (our dog) so much, I've called the suicide hotline multiple times and was diagnosed with ADHD. I hope in time you, pickles and I can be friends again. I'm just so sorry." He took my letter with him and my roommate heard him crying in our bedroom so I can only assume he's struggling with guilt right now for leaving so suddenly with zero contact with me.

After reading that note he left it sends me into a panic attack, so I reached out to his mother who he is staying with at this time and she told me that he is okay and she'll keep an eye on him. I told her how scared I was and how much I want to help but am afraid of being pushed away.  All she responds with is she knows that I would be there for him and understands why I'm worried. And that she would tell him that I'm ready to talk with him whenever he is.

Everyday I make sure to send him a morning message and a night message, just reminding him how loved he is and how I'm here for him. Other times I just say to take care of himself. I think he has me blocked or is ignoring my messages cause I had my roommate send him copies of the messages I wrote to him and all he responded with was "I appreciate you all caring. I will be ok" 

I'm doing as much research as I can during this time on ADHD to gain knowledge on how we can work on this together. 

He's never just run away like this before and it worries me sick. We always were good about sitting down for a conversation about our feelings together and this is so out of character for him. All I want to do is help him but I'm afraid of pushing him away. We live with his childhood friends and they are even shocked and confused on why he's going about this the way he did. 

What advice can you give? I miss him so much and want this to work