Welcome! First step is to throw your brush i the trash, detangle curly hair slowly and patiently in sections with a very wide tooth comb or fingers only, working from the bottom up, ideally when soaking wet and drenched in conditioner.

Brushing or rough combing damages hair increasing tangles over the longer term, also separates defined curls into frizz. Some curlies like double row detangling combs.
THE NATURAL HAVEN: The best detangling comb for natural hair
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Ouidad Double Detangler | Curly Nikki | Natural Hair Styles and Natural Hair Care

Be sure to use a satin pillowcase and/ or satin sleep bonnet, do a 'pineapple' or loose braid, these all help you avoid tangles and retain defined curls. Consider using a heat free method like wet wrapping to get your hair at least close to straight, flat ironing is damaging so will contribute to frizz.

Many of us here follow the Curly Girl method, check out the stickies on this board and the newbies board. Also numerous videos on the Curly Girl method on YouTube, many from ladies with a similar hair type to yours. A key aspect of CG is condition, condition and condition some more. Use leave in conditioner to tame your curls, far more than you think your hair can take, apply to dripping wet not towel dried hair.
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