hi amy, kids go through loads of different behaviour phases so dont worry to much your gonna end up with a little horror
you done the best thing to remove him from your friend and maybe this is the reason for his behaviour, we have to be very careful whom we leave our kids with in this world when hes been like this dont loose your temper by shouting etc talk calm to him and see how he goes after a while. Did you confront your friend? how olds your little boy?? if hes old enough he could tell you about her "ways" good luck to u and ur little boy and take care