I have low self esteem and I need to fix it quick

So basically I have this very deep and troublesome problem that one day will ruin me. I'm not sure whether you would call it a personality problem or a personal issue or what, but anyway I'll give a short backstory to set the scene. In November last year I accidently dropped a hamster and was beating myself up about it for a week and was hating myself because I thought everyone would hate me for it. After about a week I made another mistake when I accidently called my friend a chav (equivalent of white trash or trailer trash in the UK). I was just getting over beating myself up for the hamster mistake when this happened. What happened next was that it all piled up and I was stuck in this endless cycle of beating myself up and being anxious about what would happen next. So then next my gf- who was the owner of the hamster I dropped, dumped me. Before this happened though I had a psychotic experience as a result of not having any sleep at all the night before, and this was when I went back to uni. So, what happened was that my personality sort of changed (took me a few days to notice) and I also hated myself and remained depressed. I was horribly insecure and was scared about people hating me and finding out the 'real' me (whatever that is).

So fast forward a couple months and i still have sleep deprivation and I'm still drifting and drifting further down and not able to be myself. It's got to the point where I hate the person I am so much that when I speak I ask myself what the real me would say here, just so I can have something vaguely genuine to say. I also am convinced everyone hates me and have dangerously low self-esteem.

So, now to the business. An hour ago I posted something I thought was funny for attention in a group chat, that was actually a bit racist and quite out of line. I posted it to get attention in any way (childish I know) rather than just taking it in my stride and learning from it positively like I usually would I don't feel any mechanism of that. I just feel dull bad guilt feelings from it. So the reason for this is that I hate the person I am now, the person I have become as a result of the psychotic experience which changed my perception of uni and myself and who I am. So why can't I just say what want to say now and be the person I am now? Because I hate that person and I don't want anyone to see the person I am now. I have an issue with one of my friends from uni that can easily be sorted but I'm just so overwhelmed and I can't cope. This post is gonna go south from here so I'll end it now but- I don't know what to do at this point because I desperately need to somehow regain my confidence, find my old self, fix all my issues and then be me- the real me. Please ask any questions about this and I will defo elaborate. I just need serious help quick before I do something so awful I cannot cope with it. It's looking bleak from here.