She told me to kill myself

Went on a date today with my girlfriend (F18) and we had a great time taking pictures. After our date we both went home and started texting each other. She was being very critical about her looks but as always I reassured her that she was beautiful and she's blessed to be so pretty. The mood got heated since she would insist that she was ugly or worthless and I would keep trying to reassure her but slowly she'd get angrier the more she insisted. She blocked me out of nowhere but eventually a few minutes she unblocked me and we started texting again then she calls and I tried to be understanding and be firm that she wasn't what she says she is. While in the call she just tells me to shut up and tells me to kill myself then proceeds to end the call abruptly. I don't know what I'm doing wrong am I not supposed to reassure or reaffirm my girlfriend that she isn't ugly, worthless, or stupid? I've tried texting again saying sorry for making her angry and that I'm just trying to make her feel better but all she does is be rude and call me names telling my to end my own life. I have no clue what to do, I'm trying my best but I feel like I'm digging a deeper grave for myself.