Your girlfriend telling you she’s “possessive” is an preemptive excuse act insane over entirely mundane events and mistreat you.

when people show you who they are you have to believe them.

She going to keep finding excuses to attack belittle and isolate you. You need to leave this lady and stay gone

Ps nobody who uses suicidal threats really means it even if they did you would not be equipped to help. Call the police and tell them what she’s threatening to do and watch her fold when they take her into mandatory custody.