I am helpless and do not know what to do

Married 15 years. I love my wife but the sex is ordinary and banal.

I cheated on my wife several times over the 15 years. I love my wife very much and do not want a divorce.

Although I flirted, I returned home to my wife and children.
The (single) girl I cheated with texted me that she was pregnant and didn’t want to have an abortion.

My world went dark, I begged her to have an abortion and I would pay and she said she didn’t agree because she was at an age where she might not be able to have children.
I am helpless and do not know what to do.

I didn’t tell my wife and I just can’t concentrate on anything and do nothing all day thinking about what to do and how to find a way to convince the girl not to give birth to the child.