Nothing she has said breaks confidentiality for goodness sake! And of course she can talk about it at home. You don't share all the details, names, specifics, but it's ok to go home to your friend, mum, husband and to say that a patient you saw yesterday has killed herself and you feel shit. Or someone has died in traumatic circumstances.
OP find someone you can talk to. You might find that you have different people who help in different ways. My husband doesn't really 'get it' but lets me get it off my chest, cry and makes me something nice to eat or drink. My Mum is a general nurse. She struggles with the MH aspect but is just so experienced at debrief and always knows how to get me to consider my feelings, my actions, make a plan for the next time and writw a reflection for my revalidation! My sister is a paediatric nurse who works in palliative care. She's fantastic, has a super dry and dark sense of humour and can make me laugh after the most horrendous shift. My colleagues know exactly what I'm going through and are always there just to chat and get it all straight in my head about what happened. Reflections are helpful to get it on paper.
Talk with people you are close to at home or friends, and talk to people who are experienced like your mentor. Talk with people who were there at the time, and with impartial people at the uni.
Good self care - we can't look after patients if we don't look after ourselves first. It's a cliche but true. Whether that's a walk, mindfulness, a soppy film or favourite box set, hot chocolate, cuddle, bath, whatever you need to help yourself.
There will be some situations you never forget. It's often a 'first'. First death, first resus, first suicide, first DV victim, but it gets easier. Not because you lose empathy, but because you've learnt how to cope and you learn how to leave it at work and switch off at home in most situations. Sometimes it's different because the person reminds you of yourself, or of someone you know. It's ok and it's normal and human.