I should really have this saved to avoid typing it out again and again.
Sledgehammer approach is, in my experience (which includes sobbing and wishing for death), the only way to deal with it.
Get plain Sudafed over the counter from the chemist. Not the combined with anything or the stuff on the shelves - the one on the shelves is a different drug and shit, you want Pseudoephedrine - and it's a fuckton cheaper to take them with 2 paracetamol from a 29p back and a cup of coffee than paying for the combined version.
Get a cold pack on your face. It shrinks the blood vessels down a bit, which reduces pain a bit and makes the next step more successful.
You will need a Neti pot/irrigation thing/child's toy teapot/jug. Specially designed is better (generally available for not much money in chemists), but needs must when you're in this amount of pain.
Always make up the salt (and bicarb)/specially designed packets with boiled water and let it cool to blood temperature. Tip your head to one side, breathe out of your mouth and let the fluid go up the top nostril until it starts coming out the lower one. It doesn't feel particularly nice, especially when the area is very sore and congested. Massage the areas (all sinuses, not just the one that's hurting the most) and try to gently blow your nose. If nothing comes out (don't force it), repeat as many times as you feel you need to - sometimes all the gunk will come out shortly afterwards, sometimes it'll take until you're sitting down in front of the telly.
Repeat the cold pack, Sudafed, etc, until you've been clear for a couple of days, as it tends to try and come back if you stop sooner.
I wouldn't describe it as fun - but it's better than feeling as if you've been smacked across the face with a baseball bat.