Why was I wrong for alienating my 23 year old stepson from my kids?

I wrote in asking everyone was I wrong to alienate my 23 year old stepson who never showed me any respect and his parents pretty much let him get away with it. His mother wouldn't let him around me until until we started our own family. My husband always went to see his son outside our house. His son moved out of town and when he turned 23, he dropped the bomb he was messing around with boys when he was young, he also had an affair with a married man in his teens and said he slept with 28 men. My husband's son has never met my children and when his son asked to meet our children I said no and didn't want him to come to the house, I didn't want this around my kids and I didn't feel safe with him in our house around our kids. I wrote in asking was I doing the right thing but keeping my distance and I was called ignorant, people told me I had issues and that he's not a monster because of his past and that I shouldn't write him off, he had a right to meet his siblings. I took the advice, let him come for a visit, a week. Guess what, he tried to my 10 year old in the basement, when my husband caught him, he violently fought with my husband in front of our two young children. I let a monster into my house, tramatized my children to give someone elses child a chance. How is a mother selfish for putting her children first? Everyone called me selfish. I should have trusted my gut instead of listening to you people. It's a shame that something bad has to happen.