What Karen said about focusing on our own needs and feelings has struck a chord with me and my own personal experience. A situation arose recently that has forced me to confront those feelings and their effect on the relationship with my wife and family. I've always been one to bury my head in the sand (I'm a man!) and pretend that nothing is wrong, but I now know that I've been suffering from depression. The low moods, fatigue and lack of motivation: I thought "Nothing to worry about, it will soon pass." I was wrong. I've changed more than I thought and I'm now getting treatment. My GP has indicated that those symptoms can cause someone (ie. me!) to withdraw into their own little world to the exclusion of others. I can't say it was a nice experience to have it pointed out to me in the way that it was, but it has made me take a new look at myself and family relationships.
There has to be a way for both of you to get the help that you need, but it's a tough one on how to approach it with your husband. Perhaps going to see the GP together? That's how we started, although it took me by surprise and I was angry at first, but I'm glad that it's now out in the open. That's the first hurdle that you need to overcome.
Yes, there will be changes in Mark that you can't undo and some adaptation will be required, but there are some things that can be changed with a little help.