Nice letter, though (as others have already stated) you are entitled to your full deposit back.
As you know, it is illegal for landlords to charge for normal wear-and-tear and it is illegal for them to claim or to tell you that your security deposit is to be used for that purpose. Security deposits are for actual damage only, never for wear-and-tear.
Your landlord is drastically out-of-compliance with tenant laws and is aware of that fact, which is why she is trying to avoid you now. More than likely (and yes, I always think the worst of people in situtations like this), she is hoping you will let it blow by, and then you will start getting collection notices for the full amount, etc. First and foremost, your landlord is not to be trusted. She is already breaking the law that governs her business.
Your desire to maintain good faith in this matter is admirable, but naive. Your landlord has no such intentions AND why would you want to maintain good relations with an obvious unethical landlord? Also, agreeing to compromise upfront in legal matters is almost the same as admitting wrong doing.
To me, your course is clear. Your landlord gave you a verbal agreement, but nothing in writing. You are prime to be screwed. Send your landlord another letter, detailing your previous conversation with her and insisting on all details in writing to you. If she doesn't do that, contact your local Tenants' Union (or similar) and your state's Dep't. of Housing and begin filing complaints. You might think that this will somehow get you in trouble with your landlord when in fact this will cause your landlord to fear you and stay out of your hair.
As a lesson for the future, this is how you rent a house or apartment. When you originally take possession of the property, you schedule a "walk-thru" with the landlord. This is be to done before you actually move-in, preferably at the same time you first get the keys. There is a walk-thru checklist form that can be had at legal supply stores if your landlord does not see fit to already have one. You then "walk-thru" 😛 the dwelling with the landlord and pinpoint at that time anything that is wrong IN ANY WAY, including items you want fixed immediately. You and your landlord both keep a copy of this form. Then, at time of final move-out (after your possessions have been moved out and after you have finished cleaning and are about to return the keys), you schedule another "walk-thru." At this time, you compare the condition of the dwelling against how it was from the first walk-thru. If everything is still as it was (EXCEPT for normal wear-and-tear), then you are entitled to your full deposit back. If items need to be fixed, they are noted, along with estimates for repairs, as these are deducted from your deposit. Either way, you and your landlord both then sign the copies of the walk-thru checklist form and everything is in writing and on paper.
