I find when I'm not being a nice person it's because I'm hurting inside and I'm acting out. Like a wounded animal you swipe out at things and roar and make messes because you're in pain. When nobody helps you through this pain and sometimes instead agitates it or says you're only imagining it-it makes it that much worst.
Can you say how it is you act that makes you feel like you're not a nice person? I bet there's a very good reason behind it and it's because you're feeling scared.
No, you don't deserve feeling like this. You deserve to get your wounds looked at, cleaned up, fixed and bandaged so that you may feel better and start acting like your nice, loveable, cuddly self again.