Not pregnancy related, although I am pregnant! Am I in the wrong? Long post alert!

Hi! So I do not know if I am being completely selfish and horrible with how I'm feeling about this situation, if you feel that I am, then please tell me politely and do not bash me!

I have two little boys who are almost 2 and 4.5, and expecting another. My partner is not very easy to approach if I have an issue or feel upset, he's volatile and defensive in the first instance so I bottle a lot up.

His mum was diagnosed with cancer at the end of last year; she has had chemo and is on another treatment now which will be permanent. She was told that she has a few years on average, but as we all know, this could go either way. It's extremely sad and awful for everybody involved, particularly her children. However the issue that I have is that it feels like my partner wants to see her at any given opportunity, more so than the little family that he's created. Don't get me wrong, I fully expect to see and spend time with her and their family, but I am finding every weekend and sometimes during the week a little too much and full on. I understand that a diagnosis such as this puts things into perspective, but he does also have a young, growing family, and I am just finding it all overwhelming.

She lives about 35mins away from us, so if ever she comes over this way to us, he's always super keen for her to stay the night and I just really do not like it. It really disturbs the dynamic at home (my little ones are such a handful!) And being pregnant it is just even more work on me. She is also really untidy and uses every cup and utensil whilst here. My partner is always really pushing for her to watch our children if we need to go for a scan or something, which is uncomfortable for me as she doesn't take their dairy & soya allergies seriously and despite me telling her what they can eat, she'll give them other things. More disturbingly, the last time she stayed she brought her box of medication with her, and I found it left in our kitchen where both boys could have got hold of it. Then, the day after she'd left, I noticed something on the floor by the baby gate in our living room, and it was one of her tablets, still inside the blister pack, but my 4.5 year old can open these and I wouldn't be surprised if my 2 year old could too. Even my partner's sister doesn't understand the need for her to always stay with us.

Because of how my partner is, I feel I have no say. I suffer with anxiety, and one of the things that I struggle with is having other people in my home as, for me, it is my safe place and where I feel most comfortable (as a child I always felt like a stranger in my parents' homes as their partners were not very nice to me) so when she is here I feel like I cannot relax and I feel really down about her pending arrival. I just feel as though my partner has forgotten about me and our children since her diagnosis but I don't know if I am being completely wrong and out of order with my feelings? I haven't explained a lot of the ins and outs, there are more things that make me feel the way that I do, but this is just an overview!

As I requested, please do not bash me if you think I am in the wrong, please just politely tell me!

Thank you in advance 🧡