Would you contact or confront your girlfriend's ex over rumors he is spreading?

My girlfriend hasn't been with her ex since last year. I sat back as he would send her racy text messages, which she wold ignore, but recently his involvement with another woman ended. Just to piss of this other woman, he told her that he was still "active" with my girlfriend and had been while he and the other had been dating. He clearly has issues and wants anyone he has dated to feel bad. I think the guy (about 40) needs to grow up and I have half a mind to send him a message to let him know that his rumors are unwanted, immature and karma will come back on him one day. your thoughts? And my girlfriend has had no communications with him since they broke up. She thought he would give up sending her text messages if she ignored them but he didn't.