Rex, I can't sympathize with you, but I can offer you a quick bit of advice. =)

First off, if you notice people are AOE crazy, Just ignore your attack combos, and Flash till your out of MP. Then Riot Blade till the fight is over. Flash generates Gear indiscriminant enmity, and AOE DPS is far lower than focused DPS, so you should be able to hold threat fully until you get the gear level gap closed.

Finally, start each instance off with a friendly reminder than you were absent for a while, and your gear level is not as it should be compared to players who have been playing since Launch. So for obsses, they should allow you to get at least Rage of Halone off before they start. (Make message a macro you can easily hit right away!)

Those both together should make your like MUCH easier in the DF runs.

Good luck!