They can check your liver and most other organs with blood tests. Whether there is - or isn't - any damage to either organs or the brain, there's not much that can be done about the past; there is now and the future.

I don't know that there's any way to tell if how you feel now would be any different in any other circumstance, since we all go through changes as we mature anyway - so I'd proceed from now and move forward, and try to learn from any past mistakes. We've all made some; that's human.

Find a doctor (or doctors) who you trust (maybe not easy, but doable) and work with them as a team. FWIW, IME, doctors are more interested in helping patients who are interested in helping themselves. If they feel you could be helped by something - chemical or therapeutic, listen, look into it, and if it makes sense, work together with them and give it a shot. If it doesn't work, or problems arise, communicate, deal with them, and find something else.

Build a support network; medicos, family, friends, pets, support groups.... Everyone here has some kind of life-changing ailment/event we're dealing with. We're all on some kind of journey, and we're working with our doctors and support networks to make the best, and the best lives we can, for ourselves and families. Focus on the now and the future; the positive. If you're a different person now than you were, is there some way you can use that to help yourself?

Doc