I can only imagine how you feel. 3 hours of sleep just isn't enough to function. I'm not sure if you've tried or would want to try the following, but here goes...

Can you whip your boob out and replace it with a dummy as soon as she starts comfort sucking?

How long has she been like this? Is she otherwise alright? DS wasn't much of a comfort sucker unless he was sick or teething. Have you also considered just saying No Boob and dealing with the fallout for a few days or however long it takes her to self-settle - it sounds like it couldn't get much worse for you than it already is?

GL and I hope things improve real soon for you.