Ted was already aware it might be a sore subject, but when she has such problem even saying it, and then admits to killing a patient, his heart breaks for her. He can't even imagine.

"I'm sorry, that must have been awful," he says quietly. He gives her a one-armed hug, and takes her hand with his other hand, giving it a gentle squeeze. He doesn't say anything else - what can you say? Just sits with her for a moment. Wishing he could do something to help her with that pain.