If you want to remain in the religion, (for social or faith-based reasons), you shouldn't DA. You should DA only if you don't believe in the religion anymore and don't want to have anything to do with them.
DA letter is not a cry for help; you won't get any help if you hand this letter -you'll just get shunned, with no sympathy for your mental condition.
If you want help from the jws, you can get it via the usual jw way: with socializing in the cong, with seeking help from elders etc. However, the only way to deal with mental and serious emotional problems is via therapy with a professional. DA would be a relief from the jw-induced pressure only, it will not be a cure from other issues.
You could consider the middle ground of fading/going inactive. That's the path I chose, for the time being at least. I just dropped off from every jw thing, and was hugely relieved from jw pressure, and able to go on with my new secular, non-religious life. I don't allow jws any access to my personal space, and they have no choice but to accept it.