Midlife crisis, ADHD, or what?

My husband and I have been married for almost 18 years.  We have 4 children - oldest 14, youngest 5.  We are both professionals, but I have been at home with the kids for quite some time.  As his job had more demands, he struggled to get it all done.  With some encouragement, he has been diagnosed with ADHD and has been on medication for just over a year - vyvanse.  Starting last summer, I noticed that he was more angry and was spending more time away, particularly away from me although he has also spent less time with our kids.  When I asked him in the fall what was going on, he said that he "did not love me" and was very angry with me all the time.  Needless to say, the time from then until now has been extremely hard.  On a day-to-day basis, he continues to come home.  We discuss very little.  We went to marriage counseling for several months, but it only became a place for him to reiterate over and over that he did not love me.  There was no exploration of why, no attempts to fix or change anything.  We stopped going, and he has told me it is "over."  Nonetheless, he has taken no actions to leave.  If I ask him about anything, he doesn't know.  Our oldest found out that we were in counseling and immediately went to him to ask when he would start caring about our family again.  It just keeps getting more challenging.  He is drinking a lot more (prob not to excess), and his sleep patterns are very different (can't fall asleep, wakes in the middle of the night).

I am struggling to understand where we are in life.  Is this a midlife crisis?  It is a result of the ADHD or the medication to treat it?  Is it depression?  No matter what it is, what do I do?  I am imperfect, and I recognize that.  I also know that this situation is not my doing.  There is something going on with him.  I love my husband and my family and remain committed to making it work if possible.  Fora and books on midlife crisis suggest that I simply hold the fort and let him come to some peace with his transition.  Information on depression / anxiety suggest I ask him to seek counseling.  At this point, I'm scared to do anything because I don't want to push him into leaving.  At the same time, it is incredibly painful to know every day that I will be ignored unless there is something he wants to discuss (usually tidbits of stupid stuff from FB, especially his old HS buddies).  There is no intimacy, no discussion at all.  I am not even allowed to discuss plans for summer vacation with him because "he isn't sure he wants to spend that time with me."

I would appreciate some feedback from those of you who have dealt with ADHD and/or midlife crisis and/or depression as to how to approach this situation.  I remain mostly hopeful that we can work through it, but I feel like we need to make some change.