It's really not a tax or financial question as there are advantages & disadvantage going down either path and much depends on the economic fallout from the election.
What it really comes down to is that you want to stay in your existing home and your husband wants to get out from under the $3,600. mortgage payment as when you add the additional $1,300. from your daughter's condo, you are now caring almost $5,000. in debt service. That equates to a minimum of $16,500. in monthly income. Also, if you have a profit on the sale of your vacation home, you will pay between 20% & 30% in tax on the gain, depending upon the state you reside in and where the vacation home is located.
Banking the after tax money from the sale of your vacation home probably won't get you anywhere near the return that you would get by paying down or off the condo as you would never be able to get a safe return anywhere near the interest rate on the condo mortgage.
When all is said & done, I hate to do it, but I'll have to side with your husband on this one purely from a financial standpoint. However, I would be careful about selling your existence residence if you aren't ready to do so, as that alone is reason enough to hang on to it for the time being.