What should you do if a loved one talking about their traumatic experience makes you feel uncomfortable ?

You can politely tell them you feel uncomfortable with them sharing there experiences and see if they have other options to go to like talking to a school counselor, friends or even a therapist at times when necessary.

It's important to set clear boundaries. Knowing your boundaries and communicating them is important and doesn't mean that you care any less about the loved one. Make it clear that you care about them, and love them, and want them to feel supported, but that you don't feel like you can give them the support they need. Refer them to therapy or professional help and let them know that you're still in their life and that they're important to you, and that they aren't a burden - it's just difficult for you to listen, and that's okay. You need to prioritise yourself before you can prioritise other people.