My ex has blocked me for some stupid reason!?

Me and my ex were dated for almost a year but then it didn't work out but we remain friends since then which is 3 years included our dating time. But then a year ago I added a friend of his on fb and we start to chat (my ex was not talking to me for some fringin reason and I wanted to know why) so yeah I asked his friend about what was going on blah blah blah. A week ago was his friend BD, I posted him a BD wish on his FB. Days after that my ex has blocked me from his FB for the reason that I'm friended his friended but it's been over a year! I dont really understand why he acted so childish about this. He called me stalker by adding his friend and that he has a new relationship and afraid that if he still be friend with me on FB it'd ruin his relationship...but wtf?. I dont really get it. He said that we could remains friends but not through FB. I told him that I respected his decision but honestly he has to be a man and tell me face to face not behind my back and through e-mails. What should I do? I'm not sad about this I just don't understand why he acting this way. I mean it's been over a year since I added his friend to my FB. Why he bothered now? Well, I might have been keeping in touch too much on FB, I meant I would posted up comments like once in 2 or 3 months but it was just regular saying like how ya been. IAnd I mean there is no secret on FB, right? So I know everything he posted on FB. So I don't really understand why he think I stalk him. I mean seriuosly? Or is he just so full of himself? He said I was trying to get him back!