Struggling with Setting Boundaries with My Mom

I have a strange relationship with my mom, in the sense of, we don't have a great relationship. I cant figure out why though, I try to remember things that maybe explain why our relationship is so distant, but I can't find it. she isn't nice to my husband, but she isn't mean either, and whenever I try to bring it up, she acts like she isn't treating him poorly. it's never off the wall mean things, it's things like, she asks to stay the night and when I tell her we can't have her stay the night because he works, she says "I'm coming to spend time with you" implying that her being there has nothing to do with him, it's like she forgets that we live in a small one bedroom apartment and his time home is just as important as mine. she also does this thing where if we have a disagreement about literally anything, she refuses to talk about it, she shuts down the conversation entirely. she tries to imply that my husband is bad for me just because he had a hard time finding work even though he was putting in several job applications daily (luckily he found a really nice job, and we're doing much better). she also conveniently forgets that my dogs we're the only reason I didn't kill myself, and she suggested that we get rid of them (we were having a hard time finding a place to live, so I get where she's coming from, but still, but we found a place so we still have our dogs). when she asked to stay the night, I couldn't bring myself to flat out say no, and I don't know if that's because of her or something else, but I haven't had too bad of an issue telling other people no. setting boundaries with my mom is difficult, I don't know what I expect to happen if I set a boundary, I don't know if she'll get upset or if she'll be fine. I think when I was a kid she was like that too, some days setting a boundary or asking a question was totally ok, but other days it was like I personally offended her. idk, I'm just kind of venting.