I have a sister who is Bi-Polar, so i empathize with your situation. She also has "episodes" her latest was her running away from here husband of three weeks... anyway....
Im not sure what to say, except i hope you start to feel better. At least you are eating right and you have your husband supporting you. I think its hard on everyone to go to the gym, lots of times i have not wanted to go, i make myself, and tell myself to stay ten minutes and if i still wan tto leave i can.
Maybe you could try some at home easy exercises untill you feel like going out again.. When all else fails, dont worry about it, it will pass...