So now I'm a QDDP?

I'm a part-time RN in a DD group residential/dayhab organization, 20 hours a week, and trying to figure out what to do. I work with a full time LPN, who's now our Acting Director, and was recently informed that for the purposes of day to day business, as well as annual meeting and support team meetings, that I'm not only qualified to be a QDDP, but will be acting as QDDP. But I'm not qualified!!!!
I hate this. I'm supposed to chair meetings and knowledgeably discuss matters I know nothing about, and make notes so that when the contract Q picks them up, he can develop a plan around them. Honestly, I spend a lot of these meetings feeling like a complete doofus. Prior to this pronouncement, I was already working 10-15 hours a week off the clock to complete my giant workload, but the conversation that contained this new assignment also included an admonition to "find a way to get it all done in 20 hours". Sigh.
Not to mention that at this point, though 2 nurses work a total of 60 hours a week, with the increased responsibilities they only spend a total of maybe 30 hours a week on nursing.

I'm feeling completely overwhelmed, and carry a constant feeling of dread.

Anyone else been put in a similar position? Any ideas? I don't want to jump ship, and I don't want to 'splode, but something's gotta give.