I am not really trying to write this thank you letter to be paired with my recommendation letter.
What is your problem with thanking the person who wrote the letter?
The woman, who interviewed me, was terrible at her job.
If someone has written a recommendation letter for you, that person has done you a significant favor and it's expected that you thank the person for taking the time to help you out. Even if you do not think the person who wrote you the recommendation is good at her job, you should still thank her as it's part of good social etiquette. Failing to do so will cause the person to think negatively of you and your reputation will be put at risk if word gets around.
Whatever. This is all a game. I just need the recommendation letter.
Try not to focus on how she did, just know that it is the right thing to do anytime someone is using their time to try to help you out. Even if she did poorly, she still meant well.