What if I've let myself hit the darkest pits of rock bottom before... and it wasn't a long time ago. Meanwhile I've lost myself completely and the only support system I had was me and PerC blessing.
You can get out alive but you can never get out into a totally different person. Like transform from INTJ into ENFP. It.is.impossible.
Been there, done that--sometimes, right when you think you've hit bottom, you've still got a very long way to go. You're right that you can't get out a totally different person, but you also can't come out the same person either. I'd never expect you to go from an INTJ to an ENFP (that would almost be giving into your shadow side). Take a look at this quote from the official MBTI site on switching types: " consider how long ago you took the MBTI assessment and whether your life circumstances have changed dramatically since then. Generally, because the MBTI tool measures inherent preferences, there is no need to take it multiple times. However, if your life has changed significantly, you might find it helpful to take it again. In addition, the newer forms of the MBTI assessment are based on the latest research, so if it has been several years since you took the assessment, you might consider retaking it. "
I mention this quote because, while it's rare to switch types, it happens, and I'm living proof of it. The rock bottom that almost killed me actually caused me to switch types as things got better. I went from an INFJ to an ENFP after admitting to myself that 9 hearing restoration surgeries failed, and that I was going to be disabled for the rest of my life. That was rock bottom for me, but it took me about two years of falling to realize it. At first, I thought my rock bottom was when surgery #8 failed, and the doctor told me, "I've only see this happen in two other patients." Every single day between surgery #8 and surgery #9, when nobody knew whether or not my disability was going to be permanent, I contemplated suicide because I couldn't handle the thought of being "damaged", "broken", "retarded", "stupid" "handicapped", and all the other lovely names given to me because of my hearing problems. I thought that was rock bottom until surgery #9 happened, and it took me a year to figure out it had failed too. By then, my pride had been so destroyed that I didn't care about being disabled and needing a hearing aid.
Losing my pride opened up access to the world that I did initially understand, caused my grades to literally double, and give me a whole world of opportunities I never would have had otherwise. I thought the world was going to end if I lost my pride about "not being a retard", but honestly, it just began for me. Shortly after, my I and my J changed from an E to a P. I don't know what your rock bottom is, nor am I saying change your type. I quite like INTJs, and I wouldn't want you to lose the good parts of being an INTJ. That said, I wouldn't consider change while climbing out of rock bottom an impossibility either. Whether or not your type changes, something about your life must change radically to get out of rock bottom. Some things will never change, hence my staying a strong NF even after getting a hearing aid. Some things have to, or you'll (figuratively or literally, depending on the circumstance) lose your life. It's only in working to get out of rock bottom that you figure out what needs to change and what's good to keep.
Maybe, this time around, you need a different support system than you think, or maybe you're underestimating what you're capable of doing. At the bare minimum, you've got a lot of support on this thread, hence all of us stepping up and being here for you. Perhaps this is me being a bit overly optimistic as well, but I believe you can do this. I believe you can get yourself out of rock bottom and make things better. Sure, it will hurt along the way, but once it's over, you'll be so much stronger for having survived it. Never forget that the people of PerC are here for you if you want us, and that the INTJ members are some of the most supportive people you'll ever come across--hence my constantly visiting the INTJ forum.
P.S., if you ever want to talk outside of PerC, PM me for my Skype. I love adding new PerC members.