Aw dreaming, sending lots of virtual hugs, reading your post is like reading an autobiography...
I used to fully believe the thing about babies not going back to the boob if you give them bottles (especially since my DS1 had tremendous problems with boob vs bottle, because he was given bottles on day 1 by the hospital without actually asking me). But I was going insane, and after 11 days (and nights) of hell this time round I was finally persuaded by my husband (and a midwife, who was very concerned about my health both mentally and physically) to give up the breastfeeding. I am not the kind of person to give up anything - after all, I carried on BF my DS1 for 8 months despite it being awful, depressing, and making me never want to go out, cry in public, etc! - so it was quite a choice for me!
But anyway the thing is, despite being dreadful and one having a crack about a cm long and probably half a cm deep that just bled and scabbed and yuck, my boobs were almost back to normal within 3 days! This is with me expressing as well - I just began gently at first and now it's pain-free. I don't really feel mentally up to going back to BF full-time yet but I've tried the twins on the boob a few times each and they've been fine - latched on just as quickly (if not quicker) than they ever did, and also pain-free (only tried on the healthier boob as yet though, still a bit scared about the other one lol). I can't believe the difference having a few days off made.
Interestingly enough I've discovered that one twin feeds in a much more uncomfy way to the other one and I wonder if it was partly that that stopped me healing up. I'm sure all advice would say he's not latching properly but as far as I can tell he's the same as his bro... But anyway, maybe I'm just lucky that they seem to be able to both bottle and boob feed after only 11 days, but knowing what I've been through I encourage you to look after yourself as well as them! If you're expressing they still get your goodness too of course. I feel sane again, like almost normal person again. But even if the twins hadn't been able to do both bottle and boob I would still be glad I'd given up. 
I'm amazed you're trying to tandem... I'd advise giving up tandem feeding for the moment because it is such a stress and you can't get them latched on properly etc. Does one twin sleep more easily than the other? Feed the wakey one first and let the other doze if possible. Or wake one first, or whatever. And I heartily sympathise with the threat of waking up your other child - so irritating isn't it! ...and you're scared of giving dummies for the same reasons.. :(
Anyhoo, hope some of this helps coz I well and truly know what you're going through! 