She already planned your marriage, honeymoon, and the number of your kids. I won’t be surprised if she had an appointment with a local funeral parlor and had them mark graves for both of them.
I have a really big strike zone and I mean reaaally big, but there are two things that manage to make me cringe, NTR and Yanderes. Still I’m going to read this to the end.
What sets Omoi-san apart from the other generic yanderes? She realizes immediately when she's done sth wrong. That's kind of a good character trait for any character in general.