How do I get my Twitter back?

[Sydney]

I've had my twitter account since May. I have thousands of followers. I had a boyfriend over Twitter. but we broke up about a month ago. He thought I was a fake, and looked up my name on Instagram. The only result was some girl who looked to be about thirteen. He was mad. And this morning I tried logging into Twitter but it wouldn't let me. I checked my email and it said I'd received requests to change the password and my account email. Since they changed the email there's no way for me to recover the password. I asked my ex, and he said it was one of his friends, but he wouldn't tell me who it was. I have no way to get it back now, I don't think. I was just wondering if there was a way to get it back or find out who took it. And if taking my account like that was illegal.