To buy myself a present for her birthday instead?

[ShiftyLookingBadger]

In brief, my sister borrowed a beloved film of mine YEARS ago. If I ever mention the prospect of her returning it she basically implies that I'm being petty and dramatic. She then proceeds to forget to bring it back. She then "returned it" but it was a different film with a similar name, I think bought second hand off ebay or something!

I'm thinking it's lost forever, however her birthday is coming up at the end of November. Considering I am in my 40's, would I be childish to buy myself the film again instead of buying her a birthday present? I wouldn't be so harsh if perhaps her attitude was remorseful about it but the fact that she has dragged this out for years and then made a crap attempt at replacing it has just pissed me right off! Not to mention making me feel pathetic for even asking for it back. Our relationship is good but fairly distant mostly. AIBU??

P.S. Well aware that this is a 1st world problem

sounds like my DB. He "bought" an item from me but never paid. I asked him for the money 5 times as I was on a very limited income and he earned approx. 5 times what I did. After saying every time that he would give me the money soon, the sixth time I asked him he said:"I bougth that from you more than half a year ago, surely I must have paid by now!". My DH and I both said that he hadn't which he refused to believe and I never got the money. I was almost the same every time I bought a present for our parents from both of us. Took months to get the money from him every single time. He genuinely cannot understand why I don't want to go halfsies on presents to our parents anymore.

SchadenfreudePersonified PM'd you

OP. Go any buy your replacement Harry Potter film.

Ah OP! Extremely petty and obsessive!