Crazy Soccer Mom (not me!!)

My son is playing on a local recreation soccer league in the boys 5&6 division. He asked to play soccer this spring and has played every spring since he was three. And really likes it. Now I have to admit that he's not that great a soccer player. He's not that coordinated and he has the attention span of a gnat or a fairly typical 5 year old. He is also the youngest player on the team because he is an August baby he missed the age cut off for the 5&6 division but I requested him to play up since he's HUGE!! He's the average height of a 7 year old and I didn't think it was fair to have him play with 3&4 year olds. Plus he would have hated it and wanted to be with his friends. OK so now you have the background. Well there is a crazy mom and when I say crazy I mean weird, annoying, and inappropriate, that I have to deal with. The first couple of practices I noticed her correcting my son's behavior. I was OK with that because he was goofing off (picking grass and staring off into space) and I would have corrected him had I been closer. But I was also annoyed because I would NEVER correct another person's child (especially one I didn't know) for just goofing off (I would correct them if they were hurting other kids). Anyway I didn't say anything to her or do anything about. I should have and nipped her damn behavior in the bub because at the next game after we lost and my son had had a really bad game (not paying attention to the ball and falling down all the time) she turned to me said.

"He really shouldn't be playing. He's not up to it."

At this same game she also berated the coach because the game started 2 minutes early and since she wasn't there on time her son didn't get to start. She also yelled at our team to kick the kids on the other team!!! See she's crazy!! I was so stunned she had the nerve to tell me that, that I didn't say anything to her and just walked away. And that's not the end either!! At the next practice she stood near me and gave me a run down on every little dumb thing my son did.

Like "Oh look now he's got his shirt over his head. What is he doing that for?" "Oh he's spinning in circles and getting dizzy now."

I tried walking away but that didn't help she just kept giving me a play by play!! Now I hate confrontation so I didn't say anything because I wanted to keep things civil for the kids.
And I have to say her son sucks just as much as mine does! Hes not the star of the team. In fact I would say he's just as goofy as my son but with slightly better focus. I really have no idea what to do about her!! It's a freaking rec league and it's 5&6 year olds!! CHILL THE FUCK OUT LADY! What would you do???? Any suggestions as to how I should handle this because ignoring her isn't working and it's driving me crazy!