I'm thinking of putting my autistic child into care and then having another child
Is there a situation that urges you to have another child?
It is time for me to fix my life/ and fix my marriage. I want more kids.
You should take care of your current kid before having another one. It's not responsible to have another one when your current kid has issues.
I think he's not my child.
You had the child, right?  How couldn't he be yours?  You should make sure your children are taken care of before considering having more.