I don’t know your whole situation and I’ve also never been inpatient so have no personal experience of what’s that like.
My gut though tells me that this could be a really great opportunity for you. You have - I think - intended to go back since your last inpatient was cut short (apologies if I’ve got this wrong but I think I remember reading something about that?) It’s hard to get into and now there is an opening for you.
I get that if you are inpatient you won’t be able to apply for jobs and go to interviews etc so it will eat into some job hunting time. But it strikes me that, if you go inpatient and benefit from it, you will then be getting into job searching/applying/interviewing etc from a much stronger, more stable and much healthier place. You could get a job next week. Are you in a good position health-wise to take up a new job right now? Or do you think, realistically you might end up off sick or having to take time off to go inpatient soon into taking up a new role, which is a stressful thing for anyone (even the most healthy and functional person who doesn’t have PTSD!)
The events for your son...I don’t know. Does he know that you were inpatient before and have an opportunity to be again now? If so, what do you think he would prefer you do now? Take the hospital place and work on getting well or go to his school events? That’s not a loaded question even though I realise it sounds like one! Genuinely wondering what he would want and whether he would be understanding if you missed some of his things or whether, if you took up the place, it would cause huge problems between you and your son etc.
Is there anything in particular that terrifies you about going back?