Hope you are feeling much happier. One thing that has bugged me reading this is his mums involvement in this.I'd give it time as I don't doubt he is took it easily either. As others have said just keep your distance, if you really did mean anything to him, he'll talk.
Anyway back to his mum, is it a case that she thinks he's too good for you? With the whole barging in during a private conversation show that she has no respect for him, and maybe even unable to make his own decisions. To me, that is the cause not that someone else may have taken his fancy. If she is controlling him like this then I feel very sorry for him as he will never be happy.
It's just a shame we can only hear one side of the story. As for this potential new guy, it doesn't hurt keeping your options open. Whatever happens in the end I'm sure you'll be happy.