monster in-law

I've been with my boyfriend over 5 years (would be 6 if we didn't have a break up) and at first I had a bit of a feeling his mum never liked me, I got bad vibes when I was around her, I don't know.... I was always polite obviously, even more so because he lives with her. Fast forward to when me and my partner first got back together (about a year and a half ago) she'd say things like 'oh I'm so glad your back' and eventually we built a close relationship. She'd also say 'I'm so happy that we're friends now' and it was great... well, since I found out I'm pregnant just over a month ago, I've felt these 'bad vibes' with her again.. she doesn't know I'm pregnant as my partner doesn't want to tell her yet as she's abit of a gossip and previous miscarriage. But Ive been hearing her slagging me off to my partner, and he doesn't even stick up for me :/ I came here today thinking they were out, to pick up a few of my bits I had at his (I have my own key as well) and completely unknowingly, they pulled up at exactly the same time! She said "we haven't even been back 5 minutes and she's already here ffs" now am I wrong for getting extremely emotional knowing that I'm here, when I'm not wanted? I feel so awkward now, that I'm leaving at the same time as my partner does for work but I go have breakfast at my mums before as I start a few hours after him. I also go back to my mums for tea now.. oh and I shower there.. but yet I'm still paying board at my partners house, to what... literally sleep in her sons bed and drink their tap water. Today he told me she's getting fed up of me "always being here" (when I work 5 days a week, used to leave for work 2 hours after my partner but got back an hour after him and that's 9-5) now obviously with us expecting we are planning on moving out but we didn't want to go until towards the end of this year when we will have a good amount of money saved. All this is just making me want to go sooner, but he won't.. I just can't help but feel like she's really going to drive us apart and there's nothing I can do about it. She's his mother and he's always going to corner with her. 😢