J.M.
Hi H.-
I remember not wanting to leave the house becasue my baby would not eat from a bottle of breast milk. He'd cry and resist, and I would feel like it wasn't working...so I'd go back in the house, room, from whereever I was listening in from and nurse him. I agree with the "just leave" idea, as long as your husband's willing to patiently wait it out and keep trying to feed your little girl. It took a couple 6 hour days away from mommy to convince my son his dad could feed him from a bottle.
I would also recommend focusing on increasing the number of times per day you feed cereal. Mix it with breast milk so you know she's getting a little extra nutrients and help with digesting (plus it's really tasty for her...I've heard older kids say their mom's milk tastes like ice cream...from a 18 months old, I swear!). If she gets better with the spoon, you may never have to go to formula, she may just start eating more foods and that will give you more freedom to have a little time away. We all need that! It took awhile, but my son is 11 months now, loves to eats 3 meals and 2 snacks daily, nurse 3-4 times for only 10 minutes each time, no bottle needed anymore. Easiest thing in the world now.
Try to be patient...and ask your husband to help you get through this...
Much Luck-J.