How do I (29 f) tell my son’s (4 m) that I don’t want her (50s f) teaching my son her radical views?

This woman is not his biological grandmother, she is my friend’s mother. We’ve gotten along until recently, when she caused am argument after continously putting me down about my mental health. She would say its all in my head and that I just needed to rebuke the devil and that everything was just the devil grabbing a hold of me. I am not religious, and all of her snide remarks finally caused me to break down and it was not a pretty scene. This isn’t super important but it’s worth mentioning.

Now, my son is at the age where he’s starting to understand the world around him. Yesterday when I went to spend some time with after work, I work third and sleep during the day, she started in on the roe vs wade case. She is super right wing but it hasn’t been much of an issue until recently, after the election. She would pick at me about voting blue to the point that I had to start telling her I was not going to talk about it.

This morning, well yesterday now, when I’m there she starts talking about the overturning. I very calmly said that I did not want to talk about three times. She kept on to the point of me yelling and clapping my hands with each word that I did not want to discuss it. She finally quit talking about it. I know she talks about these thing around my child and I do not like it. Her husband is incredibly racist and homophobic and he, I know for a fact, talks about this around my son.

I am trying to raise him to respect other people and their choices. I want him to grow up to be accepting. He will not be racist, he will not be homophobic, and he certainly won’t be disrespectful to others. I think that it’s eventually going to get to a point where he starts to pick these things up from them and I’m not going to have that.

I want to have a civil conversation, but I have trouble regulating my emotions and my anger especially. I want her to know that I am serious about the fact that if she doesn’t respect my wishes she will be having limited contact with my son. She pays for half the daycare and keeps him for long periods of time on my long weeks of work, so it would be harder on me and I’d have to pull him from daycare, but I will find a way to manage.

I do not want to remove him from their lives completely because I know they love him, but I won’t stand by and let them fill his head with their views of the world because they are backwards and determinatal to him. I want advice on how to say these things without it becoming an argument, though I expect it will anyway. I’m not the best at dealing with conflict, but this is a hill I will die on.

Any advice, or support, is appreciated.

Tl;dr: my sons grandparents are radical right wingers and I’m worried about the affect it will have on my young child and have decided to talk to them about it.

Edit: forgot to add grandmother to the title, sorry.