Kas, you are so right about sounding like Eeyore! You were doing much better there for a while, why do you think you've back-tracked and how do you think you can get back to where you need to be? I have a couple of suggestions:
1. Quit posting doom-and-gloom worst case scenarios. Anything you post that contains absolutes is just pure pessimism, you have no idea what the future holds so speaking in absolutes is just making you feel worse for no reason. Examples:
I'll be alone forever.
If I do date all that will be out there will be damaged obese men that I'm not attracted to.
My brain says this will never happen, might as well give up and get some cats.
2. Spend less time here on the forums. You did it last week and it really seemed to help you. When you did post you seemed to be in a better place.
3. Engage in your support group. That too seemed to help you quite a bit. If you feel yourself slipping then reach out to someone in the group to help get you back on track.
4. Make your life all about positive energy! Banish the bad thoughts and welcome the good ones. Again I saw you starting to do this last week and it made a difference in your attitude. So get back to that!
I'm not sure why you think no one can be happy single. I've already told you my XW is single and she is very happy. I've also shared with you that her mother's husband passed away about 12 years ago and she lives a very full life and enjoys it very much. She has more zeal than a lot of people half her age. And me as well, sure I sort of have a GF but we only see each other once or twice a month. For all intents and purposes I live as a single person, I do everything myself, and I love my life. I think you wallow in self-despair and embrace anything anyone tells you that backs up that narrative while ignoring and rejecting anything that doesn't. Why continue to make yourself miserable? You can choose to be happy.