Mom doesn't know who I'm dating

I started dating my son's best friends dads two months ago and my mom still doesn't know. I'm worried about telling her bed she despises my son's best friend and doesn't like how my boyfriend parents him. My son and him have been friends since they were 5 and they're both 16 and 17 now and she can't stand him so if she finds out I'm dating his dad and there's a chance he could become my stepmom she will lose her fucking mind.