repayment after remarry

I was divorced in 2016 and started collecting ss on my xhusbands ss (we were married (35 yrs)
after getting married in 2021 during covid i called the ss office and told them that i was married and needed a ss card with my current name,
everything was done over the phone and up and back mail mind you i always sent mine express so i have a record when they received the original marriage license.
well i got my new ss card with the correct name on it and my marriage license back in february of 2021.
march of 2022 i recieved a letter stating i owe 35g because i never informed them that i was to stop taking my ex ss payments. not only did i almost have a heart attach i had to go into the office with all my paper work and as of today its still not clear to me why i owe anything. if they stopped my ex ss payment and clearly added my own i would have been getting more money . so i am thinking they owe me money because i was under payed all the months.