Help? im datin friends ex...but he keeps talkin bout her?

Mi friend cheated on her guy....so after they broke up...i started to go out with him and she didnt care at all...but its been a month and just recently he has started talking about how he wants to revenge her for cheating and wants to kno all this stuff about her.... like do u think he hasnt gotten over her and still likes her or? im confused >. >