I don't agree with the way a friend disciplines her son.?

Her son is the same age as my daughter (2 1/2), and every time we have met for a playdate recently, I just cringe at the way she speaks to her son. She yells and tells him she will pop his if he doesn't do what she says. She uses empty threats, telling him that if he does x one more time, then y won't happen, but she never follows through. She says things like "what would your daddy think if he saw you acting like this?" or "I'm not gonna buy you (insert name of toy here) if you do that." or she tries to bribe him to do something by saying she will buy him something if he cooperates. And then, everytime he starts throwing a tantrum she says "I don't know what has gotten into him." when he has acted like that every time I have been around. I just tell her "he's 2, he's acting his age, this is normal, it will p." I have an 8 year old son, so I have been through the terrible twos before. But she doesn't seem to change the way she treats him. I believe he would act so much better if he was treated better. And then, she had him in a high back booster without the 5 point harness system. I told her I thought he was too little for that. She told me that he won't fit in a regular car seat (BS cause my son sat in one until he was almost 4). But I told her that I meant he is too young to only be strapped in with the seatbelt. He kept taking the seatbelt off and she said to him "do you want to die? If you take it off you will fly through the windshield and you will die. Then mommy and daddy will be sad." That's fine for a 4 or 5 year old to hear....but a 2 year old can't comprehend death. So I don't know what to do....I can't just never be around her again because her husband and my husband are friends, but I feel I should step in and do something, but not sure how to approach it without offending her. Oh, and she leans on her son for emotional support. Her husband is deployed right now, so she said that her son is her replacement for her to sleep next to, and she won't leave him with anyone to go run errands because she "needs' him. And to top it all off, she is pregnant, due next month with another boy. I really hate to see her keep raising her son like this. I can't stand to watch it anymore. Any tips to help this poor boy?