My long lost ex best friend has returned?

I have two best friends, rosalie and ansley. i had another best friend, lena. my mother died my senior year of high school from cancer and i was legally emancipated. lena left the day before my mom's funeral. there was no note or anything. i had no idea where she went. we didn't talk since my mother died. it felt like she didn't care. my friends, rosalie and ansley, started to hate her while i couldn't bring myself to. i just didn't care anymore. now after four years she is back with her boyfriend. she has been trying to get us to talk to her but i just can't. i want to yell at her and tell her how she made me feel but i also just want her to comfort me again. what should i do?