What you are going through is normal, or at least I think it is as I am going through the exact same thing too!
Supressing feelings for a awhile to try to mitigate the damage in a marriage can only last so long. Once it starts to build up, an outpouring of emotion is inevitable. The on/off stuff is maybe you (or your body) working the release valve. Unfortunately, you don't feel like you have contol over the valve.
I feel the same way and it is scary. The one thing that helps me through it is reading the funny MLC script. Remember in the end the LBS starts to think that they have MLC.
You sound overwhelmed, and for good reason.
My thought is, if you can, get a sitter, whether it be family or friends, and take a little time out for yourself. You need to recharge the batteries.
Good luck!
Hugs! (((((((((((((((((()))))))))))))))))
M:35 W:33 M: 5 yrs. Daughter: 2 yr .7/11/10 D Final: 8/7/12