I'm afraid that I've kept a secret for too long.
Sounds tough. Is it bothering you?
Yes, it has become a burden to me.
It sounds like keeping this secret is only causing you pain. It's time to stop hiding this secret, tell someone about it.
I can't tell anyone! I'm too ashamed.
You shouldn't hide something because you're ashamed about it. Being open about it is a way to get past your shame. You might feel better if you tell someone you trust.