Crossroads

I am coming up on a crossroads in my life.  I have a husband that loves me more than anything and I know that.  But in the midst of dealing with his issues relating to (non-diagnosed) ADHD and life in general I do not like what I have become.  I need space and time alone to find myself and get back to what I once was which will help our lives more than anything else.  The rub?  I know that a separation will destroy him.  Even if I explain that this is what we need to help our marriage survive he will see it as an end and give up.  So, once again, I am putting his needs before mine.  I am taking care of him and my family and letting myself fall to the wayside.  I am trying to devise a plan to stop this and to put the attitude of "taking care of myself will help everyone".  This is very difficult for me to do as I have always been the care giver to everyone.  The thought of hurting him is devastating to me but the thought of doing nothing is worse.  

I am seeking advise.  Has anyone out there been in this situation (relationship is not abusive but simply dying on the vine) and come out the other side?  How did you start the conversation with your spouse?  How did he/she respond (I know that mine will fall into a depression)?  How do you convince them that this is what has to happen before everything (including me) falls completely apart?  I am terrified that I will be killing my marriage in the effort to fix it.