I would say, like Jhogan, that you really should seek out professional help if possible. The problem, as you probably are well aware of, is that it is a down going spiral. You really need to find a way to break the spiral fast.
Be honest with yourself. Do you want to break out of the spiral?
When you decide that you indeed do, and only then (no point before), start to take action. In baby steps!
In any of the steps, if it's too much just go back, but try again very soon (dont fall back to the spiral).
Just go outside your door. Then stand there for a minute.
Walk around the house. Take deep breath (try using your belly not your shoulders to breath with.
In the beginning it's all about breaking out of the spiral, not to actually do anything. By walking around your house then back, you are taking control of your life in a safe way. It also loosens the boundraries of your house as the only safe place.
Remember to relax shoulders and to breath calmly and naturaly (again try using your belly).
Next if you have anyone you trust, have this person come over and repeat the first steps with them at your side. This step should reverse the sense that interaction with other people is only safe inside of the house.
Try to spend longer and longer time outside your house (but close to it in the beginning). Again if possible have someone spend time with you outside the house.
Try closing your eyes (for prolonged time) while outside, building up a sence of security in yourself and your surrounding without having to actually see it.
Be creative. Anything you can figure out to do actively reversing the spiral have the sole purpose of keeping you active and aware of your problem.
Realize the seriousness of this problem and that for long time forward you will have to actively find things to do that reverse the spiral.
Don't feel comfortable in any step and stay there. You will need to find new steps to walk for a long time. Aikido might be one such step, but only after many others have been taken.
I'm no professional in this field, but these are generaly accepted measures to take to reverse similar spirals.
You have to be the one to take the steps. No one else can do it for you.
Good luck.
/J