I've been there and unfortunately all you can do is wait do is wait for it to grow out.
That being said, with good, moisturizing products, it WILL get better, but the curl won't come back, maybe a slight wave at best. I say go ahead with straightening but make sure you use a good heat protectant. The damage is done, focus on babying the regrowth.
Loves protein and oils
Low-poo: MopTop gentle shampoo
Co-wash: CJDF, Jessicurl Aloeba
RO: Jessicurl Too Shea, MopTop daily conditioner, CJ rehab, CJ strengthening
DT: Jessicurl WDT, SS Deeply Decadent
PT: SS protein treatment, Ouidad 12 min
Oils: argan, sweet almond, jessicurl oil blend
Stylers: SS firm hold, SS curl enhancing jelly, Kiss My Face Upper Management gel, AG Recoil