Would it be bad if I asked to stop training the new girl?

My manager is on an extended mothers day weekend so I thought I would ask here instead.

I work for a very very small company used to be 9 employees, currently 12. When I was hired my boss emphasized it's like a family here, and I can honestly say I've always felt it. This company has been so great for me.

Last year, we had an employee quit and we had to hire the first new employee since I started. Then we got a new client and hired again. We currently have 4 new employees.

The oldest "new" employee Sarah recently had her work audited and it was discovered that she was performing quite poorly. My boss asked me to work with Sarah whenever I had time to. I worked with her a bit sporadically, but I was working with her and explaining things. I was looking over Sarah's accounts last Friday and I realized they were still pretty terrible, so I asked my boss if I could spend two solid days doing a sort of bootcamp with Sarah to help her improve.

I came into work on Monday and my boss told me a different one of the new girls Leah would be changing roles with Sarah because my boss felt Sarah just wasn't cutting it. She asked me to train Leah and I agreed. I am also kind of the go-to tech person around here. I'm actually not technologically inclined--I'm just the person who switches it off and back on again or tries a different cord--which no one else thinks to do.

This week I have overheard multiple conversations from the 4 "new" girls about how horrible I am. They're complaining amongst themselves. They complained that I created this whole mess by reporting back to my boss that Sarah was performing poorly. They complained that I shouldn't be training Leah because I primarily use a different software for my accounts. They've complained that they don't want me visiting their part of the office and trying to be friendly with them.

I'm simultaneously surprised by the audacity of talking about me so loudly without a care as to if I can hear, and also very hurt. I care so deeply about my job and I have always tried to do my best for the company and every employee. That's why I asked to do a two day bootcamp with Sarah to try to bring her up to speed--I wasn't trying to get her in trouble--I was trying to save her job.

Now going forward, I will try to be more to the point and less friendly when I am in conversation with one of them. I recognize that they are my coworkers, not my friends and they aren't required to be. I just question if I should be in charge of training them if they clearly do not want me back in their part of the office.