How can I miss you if you don't go away?

I am an introvert. Essentially this means I need time by myself to recharge my batteries, and be able to cope with my responsibilities and enjoy being around the people I love. I also suffer from clinical depression. I am on meds, and am mostly stable, provided I take care of myself.
The trouble is I am not taking care of myself. I don't eat very well, and am a bit of a stress eater when it comes to dealing with the day to day stuff. Fat, sugar, salt, and caffeine are my food groups lately, and that really isn't helping me maintain my equilibrium, emotionally speaking. I am overweight, and gaining again after losing a fair bit of the pregnancy weight last year. Sigh. I haven't been getting much exercise, other than chasing the kids around. I don't read for fun as much as I used to, and I haven't been doing my jewelry crafting. My house is a mess, even after hours of cleaning, so I have been getting that apathy derived from the futility of my actions. I have been crying too often, for trivial reasons, and I really hate that.In short, I am in a funk.

I don't want to be a drama queen, nor bring people down by wallowing in my own misery. My family have their own problems and I don't need to add to them. My kids need me, my husband needs me, and I need them. My amazing, challenging, and very high maintenance little boy is running me ragged. My daughter is sweet and growing more curious and adventurous every day. I worry that I don't do enough for my son, that my daughter is showing signs of developmental delay that I am not worrying about enough, or worrying too much about. That I am neglecting one or the other. Or that I don't respect my hubby's needs because I am too focused on the kids, or my own misery.

The trouble is, I also need me. Alone. I am not getting the me time I need to keep steady. I don't know how to remedy this without feeling like a whiny baby, or an antisocial jerk. My husband is more of an extrovert, and is not happy being alone. He knows, at least in theory, that I need that time, but he also has trouble doing anything alone, and I am the person who fulfills that sidekick role most of the time. My children can't be expected to understand my need to get away from everyone, they are really too young to get it, and when I do try to get those times away, my hubby doesn't get that I need him to keep the kids away. He works outside the house, and to him, having the kids around is a treat, so he has told me. I don't know that he understands entirely how tired I get of having to serve the needs of them and him.

How do I carve out a space for taking care of me? All of the books, resource people, even family and friends say I need to take care of myself in order to take care of others. How do I do that without being selfish? How do I find time without depriving my family? It isn't that I don't love them or want to be with them, but it remains an issue that I can't be with people, even the ones I love, all the time without going over the edge. In a few weeks, my son and hubby both will be home for the summer. Then what? Will I get more time, since Daddy will be around more? It doesn't usually work out that way. He has his own plans and priorities, and although he tries to be helpful, a lot of the time he seems to want to schedule me for plans that suit him more than they do me.

So how do I make this time for me that I need? Most of the stuff I want to do with that time is at home. I feel guilty when I wish he would take the kids somewhere by himself, but when I try to lock myself away in the spare room for some crafting, or work in the yard on my gardening, the kids or the hubby always manage to guilt me into coming out to do something for or with them. How do I change this? I seem to have advice for my friends, but I just can't seem to come up with anything for myself.

Okay, done whining for today.