Thanks SerenityLove I ended up calling my Mum and calling her on it and she totally tried to down play saying it was just a flippant comment as the strained relationship between my brother and I is so frustrating for her to deal with. That she didn't really mean it and they had talked since and weren't going to let me brother around- I told her I believe that she was just making that up now that she has been caught out. Either way I have cancelled her looking after him and we will be doing a family holiday instead.
Things just continually go up and down for us. She says she wants to start again with me have a clean slate and move forward... I just don't like the woman and don't trust her. I yearn for an uncomplicated relationship with my Mother but I just don't see it ever happening.