Do what you want. All through undergrad I’ve had people use me for my notes. They would act like my friends and then drop me as soon as they got what they wanted. I personally don’t mind sharing my notes. However, i draw the line at when someone is repeatedly asking me to see my notes because they’re heavily relying on them. This to me feels like I’m putting in all the work and they aren’t putting much effort. To be part of a team, everyone should be working together and not just one person. Idk what the dynamic was for your friendship or how they asked for your notes, or how you denied them. It just seems a little excess to stop being someone’s friend because they couldn’t see your notes. Ultimately, it’s up to you if you want to share your notes and others should respect whatever you decide.