Awww, that's a shame, but probably for the best.
Just for reference, we had mycoplasma a couple of years ago, and we
did decide to cull.
We bought a dozen new POL birds from a large local supplier. We quarantined them for a couple of weeks, and all was well. However, shortly after putting them in with our other birds, they all came down with Myco. I believe that the new birds were healthy carriers, possibly due to vaccinations they had as chicks (not sure). Our original birds were all home-grown, and evidently hadn't been exposed to that strain previously, so they went down like flies

.
We culled all the affected birds (really traumatic

), then re-homed the new ones and the still healthy old ones to people who didn't already have hens. We then started again with day-olds, and frankly it's taken us 2 years to get back to a healthy laying flock. We also only buy in new stock as hatching eggs now.
Why did we cull? Well, we found out that turkeys and peafowl are very susceptible to myco, so if we kept hens who were carriers, it would pretty soon transmit to the peafowl, and possibly stop us from selling any peafowl, or from having Christmas turkeys in the future.
Of course, we'll never know whether this was the right thing to do, but we are where we are, and I'm ok with that. However, I would say that if we'd only had hens, I absolutely would have just treated with Tylan and only culled the worst affected.
You have my sympathy in any case. Let's just hope this was a wasp sting or similar, and that none of your other birds are affected

.