My wife and I were both eligible for our own retirement benefits. We are both full retirement age. Her retirement benefits were more than mine. Do I get an additional benefit on my retirement payment to equal hers? If so, what happens to that benefit if she dies? Does it continue or does it shift to a widowers benefit at that point?
No, you don't get an additional benefit to your payment because hers is larger. However, if hers is FAR larger, you may want to see if switching to a spousal benefit would be more lucrative than sticking with your own. Note that a spousal benefit is never more than 50% of your spouse's primary insurance amount, so she'd have to have a very large benefit, compared to yours, for this to be worthwhile.
If she were to pre-decease you, you could likely switch to Survivor benefit, instead of your own, which is usually 100% of what your spouse was collecting. You don't collect hers and yours, but only the bigger one. This 'widows' benefit is not automatic, so you will have to proactively apply for it if this tragedy were to happen.