Am i over reacting or?

would you have done the same thing? i left my son who is nearly 5months old with my father for 10 mins while i ran down to get my daughter from day care and when i walked in the door i found him puttin his alcho in my sons bottle to shut him up! i went off my head and literaly threw him out my front door and off the verandah, he is no longer allowed on my property or any where near me or my children. i latter found out that it wasnt the 1st time he had done it, he admitted to my mother that when ever i left my kids with her for wat ever reason he had given it to them then. im am extreamly pissed off and disapointed in him. is this wrong of me? how would u deal with it?