I rang my friend to say I really want her to come and her daughter (my other friends and children are coming too) but I couldn't extend the invitation to her 11 year old son because of past incidences which she's aware of (and apologised for).
She said she understood and would try to get a play date for him for that day. Now I just feel mean. But the truth is I simply could not invite him and enjoy my birthday worrying about what he might do as she never supervises him.