He still texts his ex?

Ive been seeing this guy for a month now. He told me he was seeing someone who he had broken up with when we first started dating. I though she was out of the picture, but i see him texting and on his phone every now and then.

I happened to see his messages one day and it looked like he was telling her to leave him alone one day, but on another day he is still replying back to her. Im confused. I saw that he screen shot a picture of a cute/sweet message she sent him a while ago. He said he blocked her on snapchat but he still text her.

I see her saying that she will text him when she wants ro be fucked but he said dont, and she said “or what”

Any advice on this ladies😞