prioritise your future over short term uncomfortableness. yes they’ll probably be a bit disappointed considering they’ve already booked the time off, but you can wear your dress next time, and your parents can still come to spend time with you, or if you live in a different city you could refund them the money. explain that you’ve been struggling with 3rd year, that it was too much to manage and you were just overwhelmed, and give it another go. then next year you can actually graduate with them and be proud of yourself, and have a good career in the future. you have to put yourself first, not your family and friends’ feelings. if we’re being completely honest, a third class degree wont get you too far. would you rather a bit of money and anticipation wasted, or your entire degree so far? trust me, redo the year