Why does he send me dirty text messages?? Please help!?

Ask him to stop. Tell him it seems odd to you because it seems out if character based on what you know from the time you have spent together. Keep in mind he was in a 12 year relationship so his habits are based on how he won his ex in high school. He missed the whole socialization of being single in his twenties and he doesn't know crap about women. He knows a lot about one.