We’ve all had bad relationships in the past! ( who hasn’t ?)
You are lucky to have two men asking you out at the same time! My advice is follow your heart and go with the one you love for didn’t they say love conquers all?
There is Nothing wrong with him having an 11-year old son and absolutely nothing wrong with him being so much older than you! If he loves you and treats you well, go for it!
Be nice to his son but don’t try to take his mother’s place (at least not right away as that will come with time).
Be his friend first and everything should fall into place sooner or later.