What happened is that when your wife started Medicare, she probably left your HDHP, so you no longer had a Family HDHP policy but a Self-only policy.
If you have her with Family coverage for the first 6 months and you with Family coverage for the first 6 months and Self-only coverage the last 6 months and you contributed $8,000, the $1,750 is exactly the amount of the excess, because your actual annual HSA contribution limit was reduced to $6,250.
I can't address which way would have been better to do it, because I don't have all your facts, but if you still have the money in the HSA to withdraw the $1,750, you can withdraw it with no penalty if you (1) tell TurboTax that is what you are going to do, and (2) contact your HSA custodian before April 15th(see footnote***) to request the withdrawal of excess contributions (use this exact phrase).
Yes, you will owe income tax on that $1,750, but the HSA custodian is going to send you a check for the $1,750 so you will have the funds to pay the tax.
Oh, next year, you will get a 1099-SA that lists the earnings on the excess contributions before they were withdrawn (they will be added to your Other Income), but with things the way they are, this is not likely to be much.
***In IRS Notice 2020-18, the IRS has announced that for HSA owners, the last date for contributions for the previous year has been extended to July 15, 2020 (this year only). One presumes that other due date-related items like the last date to request a return of excess contributions would follow suit.
[Edited 3/24/2020 4:45 pm CDT - updated date]
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