If you two aren't together anymore, why do you still care who he's seeing or talking to? Anyway this sounds like headaches and drama only. His new gf is not very mature either, and has to call you to rub it in your face that she's with him just to get your on edge and jealous only. Maybe he had her up to it, to call you. Some exs crave drama like that and will make their new gf/bf call you just to start shiet with you over the phone. Pretty pathetic and immature if you ask me. But if you called him after you learned they are together now and he ignored you, shouldn't that give you a hint? You deal with it by cutting off contacts and delete him from your cell phone, change your number too if you have to. I personally don't call to keep in touch with any exs or guys I use to talk to just because they might be in relationships and I wouldn't want to interfere in their new relationship. But if you like to be part of the drama and want to compete for him still, by all means go ahead. But just keep in mind, that if the ball isn't on your court and in the end he chose to be with the other girl instead, you're the one that set yourself up for failure and heartbreak. Nobody owes anybody any explainations, even after a breakup, sometimes things are just better left unsaid, and it is what it is.