How to deal with step kid that have never been around PLEASE READ AND HELP

Okay…as some of you know me and my husband have trying to have children for many years now. At first we thought it was me…now we know its my husband. He had a zero sperm count, BUT He has an 8 year old son that he had when he was 19 and hasnt seen him since he was 1 years old. His sons mother sent him a certified letter (after 7 years) asking him to sign permission for there son to travel to another country with the little boys grandparents. My issue is NOW my husband wants to see him now that he knows its going to take us longer to have children if all goes well. He wants to write a correspondence asking to see his son at least once a week and then he will sign for permission for him to leave the country. We are financially doing okay, but we have several school loans and other bills to pay so we are barely making it. I know if my husbands requests to see his son they are going to ask for more child support. They never established an amount for my husband to pay for child support he just automatically sends money every month for the past 7 years without seeing his son. I know I’m feeling a little selfish because I can have children and now this little boy that neither one of us know might come into our life. HOW CAN I DEAL WITH THE FACT THAT WE MIGHT NOT EVER HAVE CHILDREN OF OUR OWN BUT YET HE HAS A SON OF HIS OWN AND I MIGHT HAVE TO ADOPT? PLEASE HELP ANY ADVICE FROM THOSE WHO HAVE STEP CHILDREN PLEASE??