In-laws really seem to dislike me or disrespect me and my partner doesn’t seem to care

Me and my partner haven’t been together ‘that long’ being 10 months, we accidentally got pregnant 3 months into it as i had been told I’m infertile due to medical complications. My In-laws never spoke to me until they found out the news, since then I’ve felt something feels off. We havent known each other long and we’re technically still getting to know each other but since he’s moved in his mother has been none stop calling, pestering, focusing more on their grandchild than even trying to build a relationship with me. They asked what we need for the baby and i told them months ago yet nothing and its almost his due date, my parents have spent a lot so far and so have we but its radio silent from them. They asked what i want for my birthday and just got what they wanted for my birthday which made me feel like then why did they ask just to not get it? I just feel like they resent me because i took their son from them in a way and its like they’re blaming me for it, i dont really know what to do at this point I’ve tried to invite them out or go for coffee. They dont talk to me rather talk through my partner and when i bring them problems i have with it up, he disagrees and makes excuses for their behaviour and we constantly argue over it which is ruining my mental health. I need advice honestly..