Finding out

I found out that my husband liked children the day I got into a foreign country. I am currently going to be away from him for 3.5 months studying in another country. We both agreed that this would be good for my education. He gave me the call that day and said that he had something to tell me. He said that he had been sending sexual texts to thirteen year old girls. He told me that my dad had given him until that Friday to tell me and then he was going to tell me himself. He told me that he had asked Laura*, my soon to be step sister if she could keep a secret.

"Can you keep a secret" asked Brian*, my husband
"Yes" stated Laura
"I mean really keep a secret just between you and me" said Brian
"Yes" texts Laura
"How far would you go with me? Do you find me attractive?" asked Brian
"What do you mean?" texts Laura
"What didn't you understand?" said Brian

This apparently was not the first time this had occurred. Brian was going to watch the girls while my parents went out of state and he told the girls that they could "get drunk, watch porn, and play strip poker if they wanted to".

I also found out later that he had been discussing his sexual fantasies with Laura and even talked about a "woman's fluid orgasm" more than once. I also found out that every time I had left the room he had turned the conversation to sex.

I don't know how to feel about this or what to do.

*Names have been changed