If your curls have not been right since the day you straightened and jumped in the pool TBH the flat iron is likely more at fault than the pool water. Although chlorine won't help your hair's health you cannot kill your hair in one swim, you absolutely can in one session with heat, all you need to do is use too high a temperature or straighten even slightly damp hair. Have you stopped flat ironing now?
2a-2c, medium texture, porous/ colour treated. Three years CG. Past bra strap length heading for waist.

CO-wash: Inecto coconut/ Elvive Volume Collagen
Treatments: Komaza Care Matani, coconut/ sweet almond oils, Hairveda Sitrinillah
Leave in: Fructis Sleek & Shine (old), Gliss Ultimate Volume, various Elvive
Styler: Umberto Giannini jelly, Boots Essentials gel
Flour sack towel, pixie diffuse or air dry.
Experimenting with: benign neglect