Me and my boyfriend broke up about 3 months ago, we were together for less than a year, and he wasn't there for me at all when I had a close family member die. We were OK until he started iming me, I just didn't want to see him- I feel so let down by him, saying that he was having a horrible family time, not half as bad as what was going on with me, and he said he wanted to meet. I told him no, and he started giving me loads of hassle. A few months ago I had told my "friend" how I felt about him, how angry I was at him and hurt and this got back to him, not what I said. As you know about Chinese whispers.
Anyway he's giving me loads of hassle, saying what a b**** I am, how I wasn't there for him, failing to notice that he wasn't there for me at all. A couple of weeks ago I started going on dates with a very nice guy, who I've known for a while through friends. There is no way he would know about this unless he talked to one of my friends, which I know they didn't or by checking my social networking site/email.
I've changed my passwords but he keeps saying things to me that it's the only way he could find out.

What should I do?

You ignore him and get a life you are happy with.

Don't pay attention to gossip and drop friends who talk behind your back.

Ignore him, as in no more contact, then it won't matter what he knows, or how he knows it.

This bothers me because it is too close to what happened to me. I had no contact with my ex, yet I would find out he knew things about me - that I was dating someone new, that I had gone on vacation to visit an old college friend, etc. I would be very cautious if I were you. Is there any possibility that he is following you? Let those close to you know about this, and be sure to keep your eyes open as to your surroundings. For now, don't post things openly on the internet that you don't want him to know. Think about ways to protect yourself. My situation became dangerous. That may not happen to you, but it never hurts to be cautious.