I actually think it will be good for him to get comfortable to with different people grooming him. It sounds like she probably made him hate getting brushed even more, so it's good you'll be finding another groomer.
I think basic desensitization is the way to go here. Start when he is relaxed. As someone else suggested, you can just rub the smooth side of the brush on him so he gets used to it. I would not force him to deal with it. Do it until he gets uncomfortable or for a few minutes, whichever comes first. Give him a treat afterwards and praise him. Stay very calm. Do this every day until he is calm around the brush. Then start actually brushing him, again just for a few minutes at a time. If you do this every day for a month or two, I would bet money you will have a big brushing fan on your hands!
I can't find Chris Christensen products where I live, so I just started using Bobbi Painter's 'Snarly Dog' detangling spray. I'm pretty happy with it.
Good luck.
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Chattiesmom and I posted at the same time, I agree with her suggestion.