I recently read somewhere that says "Mom has gotten a divorce since 1980". Is it correct to say so, and is "Mom has been divorced since 1980" also correct?
English verb tenses can often be confusing, but the problem here is phrasal verbs. Both of those sentences use the present perfect tense, which is used to talk about single events that happened at some time in the past or to talk about past events that have continued up to the present. It's the use of the verbal phrases "to get a divorce" and "to be divorced" that really tell us what the writer means. To get a divorce is a one-time event and to be divorced is a change of status that continues to the present. So, "Mom has gotten a divorce since 1980" means that at some point between 1980 and today, Mom got a divorce. You'd use this phrasing if you were talking about what a horrible marriage Mom had in 1980, but don't worry, Mom has gotten a divorce since 1980. "Mom has been divorced since 1980" means that in 1980, the divorce event happened, Mom's marital status changed and has remained this way until now. She is still divorced. Both of those sentences are grammatically correct, but are talking about two different things.