Infidelity Support Group
Any relationship in which one partner engages willfully in sexual relations with another outside of the partnership is considered to have experienced infidelity. This breach of trust is often traumatizing for the faithful partner as well as the relationship, and support is often needed to heal emotionally and to decide whether or not the relationship should continue after...

Make a plan, get your assets together, and ditch this creep!
Reaching out to people can be done as easily as Facebook-ing or Skype-ing. I know it's how my stepdaughter reaches out to men for sex. It always starts out with conversations, then showing themselves naked, then meeting for sex. She can find a 'date' anywhere she goes on vacation. There's nothing we can do about it.
You just need to decide if this is acceptable to you or move on.
My concern more would be what STD is he potentially bringing home to you. I would not trust him unless he got tested and you can see the results personally. Even then, whose to say, next time he won't care.