To aggrieve someone is a lousy thing to do. Not sure why? See the "grieve" in there, and you'll see why. It means to bring someone sorrow.
Which one of us is the aggrieved party? Well, considering it was you who let your pigs run roughshod over my lawn, I think it's clear that it's you who aggrieved me. Or, to put it another way, I've been aggrieved by you and your horrible hogs. When you're talking about interpersonal issues, to aggrieve someone is to hurt their feelings, but in the legal sense, it means something slightly different: it's not feelings that are hurt when one is aggrieved, but one's rights.