Built and lost bankroll

[motifesta]

I am playing $1/$2 NL on PokerStars. I consider myself a pretty solid player and have built up my bankroll twice now and lost it all both times. I built my bankroll up to 4x my initial deposit and managed to end with $0. I think I have a problem. I can't seem to walk away at any point. I will play for hours upon hours. I usually do well, but I have also had brutal losses. I had the worst run of cards today... the worst. I didn't have a winning session. I lost $800 in about 6 hours. I know most of you are thinking "move down limits." My response to that is simple- I feel comfortable at $1/$2. I do well... I just think I have a problem. I think I can't walk away when I'm on tilt. I allow myself to keep playing. I'm going to go broke if I keep this up... I honestly can't believe I lost everything.