I miss having real feelings for someone I'm with, how can I change that?
It's possible to change that, but you have to ask yourself how it felt when you used to have feelings for them?
Tingly. Wanted to hold her forever. Wanted to be kind always
It's good that you love to have such feelings for someone, but you're too attached to that ex. If you still feel such things you should break up with your current because you will only bring things down with these old feelings.
I just don't want to be hated but I feel better since I told myself that I have to be alone forever.
You might just not have found the right person, which is normal for people.  Once you find the right person for you, you will know.