Navigating Change After Loss and Remarriage

So my mom, 46 female, is getting married again next month. I,

15 male, am happy for her. My dad passed away last summer, and it broke her.

Those first months were really dark for all of us, but especially for her.

Eventually she started dating again, and now she's getting married at the end of this month.

I am genuinely happy for her. I want her to have someone who loves her and gives her

the stability she lost. But honestly, I'm struggling with some feelings that

I don't even know how to put into words. After the wedding, there's a chance

my mom will move in with my stepdad's mom. And I just keep thinking: where