It sounds like it! If he is telling you that there is no way he is going to let you take some time to yourself, that is a definate bad sign. He should understand WHY you are wanting to do this. Maybe if you explain it in a positive way, he would be open to it. He may look at it as you leaving and walking out on the marriage, when in fact, it MAY be to fix the marriage. Time apart has healed a lot of relationships. Sometimes having a clearer perspective does a lot of good for both people involved. If you are worried about him never taking you back, and you want that to at least be a possibility even if you ultimately decide to walk away, then you should maybe try to explain it to him in a different way. It's not leaving, it's having some mental recovery time.
You didn't say how old your kids are, but it is important to communicate some of that is happening, in a mature and factual way. Don't blame him for anything or say anything bad about him, just the facts of the situation. Kids can handle a lot at a younger age and appreciate honesty from their parents. When they are adults, they will always remember that their parents treated them with respect, which is very important. You shouldn't feel guilty about wanting happiness for yourself. If you are in a stressful situation, remove yourself from it. Even if for a little while. Don't play around with your health concerns!