Is it okay when in a serious relationship to have several women calling, texting and chatting daily?

I am having troubles, not because he is friends with his exes, but because they are constantly calling, IMing, and asking to visit. He is in constant contact with several of them and talks about them constantly. It is giving me a serious complex, and I am not sure how to react to this. He says I lack trust in him. To me it is a lack of trust that he is fully in this with me. He says that with them he was crazy about them - in an unhealthy way, but with me he is himself, but he doesn't feel crazy about me. That, and they all like three-ways and making out with each other. This is as recent as January, AFTER we met. It makes me very uncomfortable and I am uncertain how to deal with this. It seems to be a round and round battle, so I figured I would gather some data and prove to him that it is unacceptable to be in constant contact with your exe"s" while in a (at least semi) serious relationship. I could go on and on about this one, as it really bothers me, so I better stop now :)