Too much thinking.
First step: Out of sight, out of mind.
After that: Out of mind, out of mind.
As much as possible, keep a distance.
The more you are around her, the more opportunity there is to fantasize.
By "telling yourself" anything about her, you are thinking about her.
It's hard, but as much as possible, don't go there.
If you are at a shabbos meal together, don't sit near her, don't initiate conversation. Speak when spoken to, as being rude will probably also cause issues. When necessary, keep interactions brief.
It's difficult,
Warning: Spoiler!and I still have a hard time following my own advice,
but try your best to stay the course.
Moish