If you forsake your history and where you came from, you lose yourself. Like grass blowing in the wind mmhmm. Why do you think they call it your roots?
What of your potential grandchildren? I think it is best to try and move on from @AnonUnlimited while you pressure him to pay his due. Else it is not only will you be hurting yourself, but also your son.
Do you not want to be there as your son grows up? When he gets his first job? If he falls in love? Will you be willing to let him be the second he becomes an adult never to interact again? Do you want to take his mother away? No? Then don’t become a cockroachcow. It is a road that leads to death.
I weirdly enough had almost this exact same bit going on with a friend of mine. Pretended to be a divorced couple, with a kid (another friend), and I was the father who never paid child support and instead gambled on crypto