What to do in this situation?

Sorry if wrong board tips and tricks was removed so don't know where else to post. I was Cait adc and was against a thresh. My sup was vel. He fed the enemy 4 kills and rage quit. Meanwhile the syndra only complained about our performance while yasuo ganged us twice and snowballed. I suggested that she should roam and she said "I'm not your support you r%%%%%". So clearly she's on tilt and outs a 4 v 5 match. I have turned 4 v 5 matches before but when everyone is so uncooperative it's really hard. Meanwhile everytime I went to lane I'd get caught under my turret trying to farm eventually ending 0/5. What should I have done in this situation. Should I have went mid? Should I have just stayed in bot? Tips appreciated.