If a mere brush is enough to break your hair, I think the problem isn't the brushing but the hair that's too damaged. If it's not your brush that breaks it, it would be your hair elastic or something else, unless you have a brush designed to pull really hard, like those round "brushing" brushes or those tight animal hair (ew) brushes. Or so I think.
If you can without it getting too oily, wash it less often, and make sure your shampoo isn't too irritating. If needed, you can look for a "damage therapy" shampoo or something, as well as a conditioner. You could also look into food supplements with something for the hair for the hair.
http://www.gnc.com/product/index.jsp?productId=4033447 This looks interesting. Though if you want to buy it, watch it for a while, because it's gone down to 9.99 $ twice in a month already. It'll probably get the reduction again.
Also make sure your hair tools (drier, iron...) are not too violent on your hair. Dry your hair on Warm instead of Hot, for example. Look into tourmaline ceramic products. I don't know, really, but they're supposedly less of a strain on the hair. Don't put your straight iron on the maximum setting. For example, mine goes up to 210 °C, but 170 is enough. At 210, my hair clearly gets damaged. And don't use an iron when your hair is wet (boiling your hair basically, probably not a good idea) or covered with a product (many, many people iron with hairspray on, resulting in hot chemicals boiling around the hair - again, I don't know, but probably not a good idea.
I recently started washing my hair every two days instead of daily, and I've seen a huge improvement. It doesn't break nearly as much. And thanks to my trusty anti-androgen, it doesn't get oily, whereas before 24 hours were all I needed to have it slick and yucky.
