I have no doubt that you are an absolutely beautiful person, and I hope you have a fantastic time this season.
I spend a lot of my time in a surprisingly humid Middle Eastern country, and have done so for the best part of the last decade. Here are my tips below, but remember - in hot countries, everyone is in the same boat. People are far too worried about themselves to be looking at you I promise! The biggest sweat patches are absolutely acceptable here, even in very formal events - it's just a part of life.
Frizzy Hair
I wash my hair every day, and finish it off with a wet brushed in intense silver conditioner (I'm a blonde, but I'm sure you can find the equivalent if you're not.) Once your hair is conditioned, use a waffle towel to squeeze dry, reducing the moisture in it that can react with the heat.
Experiment with having your hair up for longer periods of the daytime, practice a casual up-do that makes you look elegant while keeping your hair out of your way.
I have fine hair, so haven't used a Brazilian, but many of my friends and colleagues do these regularly with a professional and it works!
Skincare
Mitchum Ultimate Powder Fresh Gel for underarms, or if you're particularly sweaty (no shame!) try Tawas powder/Alum stone on your underarms.
If the difference between hot, humid outside and dry, cool inside gives you dry skin, try cool showers instead of hot and use a decent moisturising body wash and moisturiser within 10 minutes of getting out of the shower.
If the redness is from heat rash, try using a toner. A friend of mine gets red blotchy skin in the heat (all year round!) and she uses Collodal C Oatmeal toner. I don't think its too expensive, just difficult to find in the region so I'd bring it to wherever you're off to!
For makeup, get a decent setting spray because cosmetics MELT off your face. I thought it was impossible until I tried Urban Decay Allnighter. Just get yourself a good facial moisturiser and primer to prevent the alcohol drying your skin. I'm in a different age bracket so what I use might not be the best for your skin type, but my go to routine is Kiehl's Gel Cream, then a Smashbox Photo Finish primer. I use Sunday Riley Toner in the evenings as part of my cleansing routine. I always carry round a mini makeup kit for touch ups, makes me feel more confident.
Body
You may find that maxi dresses can trap the heat and make things a bit sweaty - try a midi dress that cinches your waist and draws attention to what I'm sure are beautiful features! You can accessorise with a cardigan if things start to cool down in the evening, and wedges will give your legs definition without presenting a health and safety threat. Get yourself some big sunglasses and pretend to be a celebrity if you start feeling self-conscious. You might find that the slight separation the dark lenses give you is enough to change your perception of the environment.
I struggled with self-esteem around my body since I was a teenager, and found that I'm happiest with myself when I'm enjoying myself. Every time I have negative thoughts, I snap an elastic band on my wrist and do something else. That could be starting a new conversation, or getting a drink, or checking something online. Just something to distract me. I spent far too much of my life believing I was disgusting, and while I'm definitely still working through this - it's just time I've wasted not enjoying myself.
You also might be surprised about how your eating patterns change in hot, humid weather. I love going for olives, maybe a bit of seafood on ice, a glass of white wine and perhaps some pistachios on balmy evenings. I try to swap some of this for a fruit platter, but I'm not always successful. This can mean more salty food being consumed, which can lead to water retention and bloating - but the bottom line is, you're living your life and enjoying yourself and everyone around you is too!