I cant get along with my MIL..

My SO and I have been together for about 3 years, and I have no reason to feel this way.

She has done nothing but help us out, and be there for us when we need financial help..

Or when me and SO have a fight.. But she's always saying how I'm in the wrong when we do fight..

He slapped me once, and she said I should provoke HIM.

Some things that bother me are.

She pays more attention to one grandchild than the other.. Like even if both are over there she will clearly favor the older one over our miss 1. The older one gets everything, has special places and chairs at gmas house, where Immy doesn't have anything.

She's constantly spoiling one more than the other, or so it feels..

She has to put her 2c in on everything from what we feed miss 1, to how we discipline her.

She seems rather rude to my SIL and I. Like the other month she told us she was furious when she found out we were pregnant. My SIL was 20 and my BIL was 18 when they had their bub, but me and my SO were 21/25. We both had jobs, and our own place.

She says that I'm the best thing to happen to her son, but I feel she treats me like a burden.. Or.. I can't think of the right word, like a.. parasite?

I'm over reacting, I know. Our personalities just clash and I find it so so hard to get along with her. Its not like I pick fights or anything..

I end up just sitting with miss1 whenever we go over.

She always says things so matter of factly, not asking for input of further conversation.

Her way or the high way.

I want to get along, I don't bring up any of this, not even SO knows how I feel, but its gotten to the point where I don't call to ask for anything, we needed milk and bread, but I feel I would rather walk to the shops than have to deal with the awkwardness of her coming over...

Am I horrible for this? I feel so shallow and just horrid that I feel this way towards my SOs mother! (Not that it makes a difference but its not his bio mum, he'd been with her since birth but.. So is.. Well.. his mum lol)