Fiancé is moving in with me tomorrow, MIL has woe is me attitude

Basically the title… fiancé’s mom has been crying for weeks about the move. His parents live about 2 hours away from me. She thinks that we will never come visit. I feel so guilty because I feel like I’m stealing her son from her and that all of this headache could be avoided if I just didn’t exist. It’s an emotionally draining experience. I should be excited for the big move, but instead I’m dreading the theatrics.