I am glad you are in a better place today SoL! Still, I think it is worth venturing a response to some of the concerns you raised, because I think you are not at all alone... FWIW:
What's so wrong with wanting to live a solitary life?
Nothing is wrong with that. If it is what you actually, calmly, non-reactively want. As long as you are not forcing yourself into a box because you think it is the "best" you can get, but you'd really rather have something else. This is tricky, admittedly, we have to be realistic - AND we have to be honest about when we are settling for second (or fifteenth) best... BTW - a nanoscopic number of human beings ever choose isolation voluntarily - even famously "solitary" people nearly always maintain daily relationships with other people. Just sayin'. We are social animals. We really are.
Literally, I KNOW I'm toxic. I've tried to change, but nothing ever gets any better.
You may be more toxic to others than average in 3D life. AND you may be average and beating yourself up. OR the toxicity may be (likely is) a result of symptom(s) of the PTSD that you have not yet successfully managed. There is evidence that you are getting better. It is hard to see this from the inside very often. As a general rule we should get suspicious whenever the words "Nothing ever gets" appear in our sentences. It is just so rarely true. Everything always gets... different over time. (except maybe the laws of physics, but even then we can't be certain..:whistling: )
I hate having PTSD, and knowing that I'll have it for the rest of my life, even if it goes into remission, makes me seriously wonder why I should try to have people in my life. It's NOT fair to them to have to put up with my PTSD!
This muddles three things - One: grief over having PTSD (with you there!) because PTSD sucks (Big agreement).
Two: Worry about the effects of your symptoms on people who might get close to you when you are doing better. A worthy and admirable concern. And not really your decision. If you are honest with people about who you are and what the risks are, you owe it to them out of respect for THEM to let them sign up or not as they will. Let me say that again: You Owe it to THEM to give them the option. It is disrespectful not to.
Three: Nothing about PTSD is fair. For you or anyone else. Fairness has nothing to do with it. If you are not locking them in a room with you, you are not forcing anyone into anything. If you are doing all you can to control your symptoms and be a decent person, and take responsibility for your actions (even those done involuntarily) then you are doing all anyone can ask of ... well, anyone. What you have missed here is that it is a blessing and a privilege to be allowed to participate in someone else's life and process of healing, and that you might both offer benefit and benefit from relationships (even very imperfect ones) with others.
It's toxic toxic toxic toxic crap that nobody should have to deal with.
Yup. Including you. And as you move on in your healing YOU won't have to deal with it so much - and other people might just have something to offer to help you through...
I can barely manage by myself. I think it would be selfish of me to bring anyone into this.
See above. Selfishness is tricker than it appears... It might be selfish to shut them out... What if it was self abuse to shut them out? Is self abuse selfish? I kind of think not....
Even if I go into remission, it can come back at any time. I just don't see a way around that.
There is no way around. There is only through. And you are worth getting through, and going through with.
Hope this helps....