Cut My Own Hair

so when the hairdresser was cutting my hair, i saw a fucking lice then when i was showering i saw like 3 from my towel .... I HATE LICE,,,, ITS LIKE THE FIRST TIME I SAW LICE IN MY OWN HAIR IN 10 YEARS idk where i got it but i think its from a classmate :// im really close w her maybe its when i put my head on her shoulder thats where the lice go on mine.... i saw like little lices on her hair but not the mother (??) lice but what i saw on my hair is the mother lice or big lice or wtv its called im freaking out cuz its so disgusting HOW DO I GET RID OF IT IMA KMS how do i get rid of it without buying products,,, cuz im broek

I know this is for cutting hair/dying it but I have no idea where else I can ask for help. I have very long hair. It goes past my thighs and is a bit wavy. It's so long the curls just stretched out over time. Brushing it is quite a task and I have to wash my hair very often because it gets stuck in things, my scalp also gets very oily often which causes dandruff. I don't really want to cut it since it's the only thing that makes my appearance stand out, and I'm very proud of how long it's grown. I don't really know what exactly to do about it though. I'm not really skilled when it comes to haircare or hair styling. I'm currently using an Asian shampoo which has worked better than past brands. Any tips on how to style it/take care of it would be very helpful. I haven't had much luck when it comes to googling tips and tricks. I don't mind if there's any recommended ways for me to cut it even, I just don't really wanna cut a lot of it off.