Lied to me about the ex

So my partner of 8 months lied to me quiet abit about his ex even thow I found out everything , first he lied about how long they were together(first it was two years , then three, but I know it's four) then he lied about living together claiming he never lived with apartner(he is 30) but all along I was suspicios since when we first started dating he did not bring me to his flat since he claimd that his room mate is a bitch. Then he moved out fast after we first met(less then two months) he never admited he lived with here and when I saw the flat I saw two seperate bedrooms , but This weekend the truth came out that they did live together , one year as a couple then six months just as room mates( very odd ) and the most odd thing is that they always had seperate rooms even when they were together . And the anoying this is that they still talk often and meet each other every once in a while. And they even went on a holiday together after they broke up.