I think that it's all about how you care for your hair before and after. Before you dye, I would make sure that you're hair is MOISTURIZED and in good condition. I have 3C hair and I dye my hair fairly often. I've never experienced excessive breakage during the actual DYE process however if I didn't care for my hair afterwards, it would dry out easily. Just make sure you give your curls EXTRA ATTENTION after you dye
There is a difference between "dying" your hair and lightening it. When you lighten or "bleach" your hair, it completely opens the hair shaft. You would have to do some extreme lightening to achieve what you want. I recently got peek a boo highlights and they do not curl like the rest of my hair. If you want your curls....don't do it. And trust me, im a stylist!
I have extremely curly (type 3c) honey blonde hair and I really want to go to a near-platinum (think a shade darker than gwen stefani/marilyn monroe). Will this completely kill my hair?
I realize this is a little old and the OP never came back to report on what she decided... However, since I know new members with a similar situation might want to look in here for advice I'm going to post what I would've wanted to tell her at the time.
If the OP meant honey blond was her natural (virgin) hair color, then yes, she could've gone platinum with minimum damage because her hair would've only had to be lightened 2 more stages to achieve platinum hair. But if it had been previously lightened from a darker shade, that would all depend on the actual condition of the hair. An important consideration would be that when the roots grow in they would have to be bleached many more levels than the length did, but even so with very good upkeep it's possible to pull it off. Youtube is full of videos of girls who were originally very dark haired and who went platinum, silver or white (all of which require the same level of bleaching: pale yellow) and have nice looking hair, but the majority didn't do the process all at once but spread it out over a month or two and did DTs in between.
If the person has been following the CG routine for a while her chances are much improved too, Lorraine Massey herself had (and maybe still does) lightened curls that looked pretty healthy. CG should at least be followed after bleaching, it would reduce fading/brassiness and keep the hair much better moisturized.