I haven't been in a relationship since I cheated on my last partner five years ago.
Why haven't you gotten into another relationship since then?
I still feel guilty about what I did and worry I'll do it again.
I understand. It was wrong for you to cheat, but it's good that recognize that what you did was wrong. Accept your past mistake and move forward with better intentions.
What if I don't want another relationship?
There's nothing wrong with choosing not to be in a relationship! Plenty of people are happy being single, and if that's what you want to do then you should do it. It's important to live your life in a way that makes you happy.