I didn't respond as I was so floored. It was almost home time so I just made my excuses and logged off a bit early. I have been nothing but supportive to this person since she started the job. I don't really want to go into what triggered it as it would be outing but it was a complete over reaction. I know no-one can judge whether she was justified when they don't know the exact circumstances but I just feel mortified.
Generally have loved my job but have not been enjoying it recently and started applying for other things. Today boss had a day off and relatively new colleague launched a viscous verbal attack at me on group chat for no obvious reason, there was certainly no nastiness on my part. I just feel like I can't show up tomorrow, just want to crawl into a hole. Sorry just needed to get that off my chest.