At the end of my rope.

Today SO, little (3y) and I went out to breakfast with SO's dad. I have dietary restrictions, so we planned to grab something for me after breakfast. We needed some groceries anyway.

Breakfast was fine. The drive to the store was fine. But when we arrive sometime around 2pm, SO begins nagging me about what we are going to do since Little is asleep in the back seat. I have my period and was ravenous, so I'll admit that I may have been just a tad bratty.

Finally, we go in and all hell breaks loose. Little can't decide whether or not he'd like to ride in the cart. So after some back and forth, I'm carrying over 1/3 of my weight and trying to see/maneuver around a grocery store. I ask SO to walk in front of me because this is what we always do since I can barely see over Little's head while carrying him. This is when he decides to make a scene and demand to know where exactly I'd like him to go. I'm fed up, so I say "fine" and lead the way to the bread aisle. When I finally get there he pushes the cart into the aisle and begins causing a scene. He's ranting and raving about having to follow me around (???) and says I can push the cart (and carry the 40lbs of weight and pay for the groceries that he covers because I pay for the rent, utilities, cable, Internet, etc) because he's going out to the car. I'm not interested in being publicly humiliated, so I calmly walk out of the store and put Little in the car seat and try to breathe. SO storms out and begins yelling and asking me why I'm "treating [him] like a piece of shit." In front of my son. I ask him to stop and tell him that it's not appropriate to talk to me in this way in front of my child. He continues on and on for several minutes.

I don't like the cursing and I especially don't like the blatant disrespect for my wishes for him to censor himself. I'm worried that this behavior is going to affect my child. When we get home, he exits the car at full speed, leaving me to carry everything and Little into the house. We tripped on SO's shoes on the stairs and Little gets scared. SO ignores us. A few minutes later Little asks SO a question and he ignores him. I'm thinking about asking him to stay somewhere else for the night. He's shown callous disregard for us today and I'm hurt and very, very angry. I know he doesn't think he's wrong.

EDIT: sorry for the wall of text, I'm on mobile and am shit at formatting.