Hi Niz
As Pip and RedAlex76 have said, apologies are not necessary we all understand how you are feeling and it is good to get it out.
The mood swings, lack of motivation and loss of interest in what we used to enjoy are things that I think most of us here will have gone through at some point. I have been in very low mood for most of January and have isolated myself from friends more and more, I suppose there may come a time when they just stop asking me out, which I may later regret, but at the moment I just prefer not to be around people, even those closest to me. I have to go to work, or the bills don't get paid, but find it easier to be around people there because all my interactions with them are on a superficial level.
There are certainly things in the past that I would have done differently, which could have affected my current situation. Those things are on my mind all of the time and are what keep me in the cycle of low mood, lack of motivation etc. that you describe.