A son of 13 I have never met.
I had a brief relationship 14 years ago and slept together only once. She became pregnant & we fell out big time. She had a baby boy. She never wanted to talk to me and I've never seen the boy now 13. I've saved money every month for him & maybe get a chance to meet one day. In the mean time I'm bitter & full of hate for her.
It's difficult to understand from your short story what has lead to your bitterness towards the mother of your son. Did you disagree about whether she should have the baby, or what support you would give her? Whatever happened there is a teenager now who may well want to meet his father, and it would be helpful if you can put some of these feelings behind you so that they don't ruin your chance of a relationship with your son. If you would like to talk through your situation please contact the national helpline, or get in touch with a local centre.