Wanting to get better is a huge step forwards and you should applaud yourself for that. It's not easy to admit you have a problem.
I used to have similar feelings to you a few years ago, it was an awful time - shy, few friends only, hadn't ever had a boyfriend before, felt like a failure, ugly… the list goes on. But - ! - I no longer feel this way. I was crippled by social anxiety but now I make new friends with ease - I don't want to say too much stuff about me because it's not relevant, it's to reassure you that it is most definitely possible to overcome these negative thoughts and feelings.
You're ascribing magic powers to yourself when you think you can read people's minds and see they dislike you or see you as a failure. You aren't psychic, challenge yourself when you feel this way and look for evidence - and no, not silly things like not smiling widely enough at you. Be careful not to read too much into things using the lens of self-hatred as you'll interpret some very benign things as signs that person does not like you. Unless you ask the, or they tell you their opinion of you, you have no concrete proof that they dislike you.
Secondly, you are not alone in feeling this way so try not to beat yourself up over it. Most of us will feel this way at some point in our lives and it is NOT reflective of a personal fault. If you could see someone else in the exact same position as you now, what would you think? What would you say? I don't believe you'd be as harsh on them as you are to yourself. Show yourself some kindness, forgive yourself for being you since there's no reason why you should hold such a low opinion of yourself. You're a human capable of loving and being loved by others just like all the rest of us out here.
I would strongly suggest looking into arranging for cognitive behavioural therapy, either in person or online, as it will help you to learn how to tackle those unwanted thoughts of doubt and failure.
Change won't happen overnight, so don't punish yourself for not doing so "fast enough". Perseverence is key.
You really can do it, anon. Best of luck!