Hi everyone, finally, a place where our decision for an only child is not questioned or belittled! :)
I have a nearly 3yr old angel/terror/happy monster (delete as appropriate), he'll always be an only, there's no chance I can/should have another.
I don't tend to get the 'its cruel' reaction so much, more the 'oh you'll change your mind, I KNOW you will...' like my decision is based on something silly, that I'll grow up (I'm 32 FGS!) and forget the HELL that the last several years has been. Patronising *s!!!
I was never sure I wanted children in the first place, DH desperately wanted about 3, so we compromised by trying it once, 'to see if it agreed with me' 
So after 3 lots of surgery for Endo, I dropped lucky with my son. At 10 weeks I developed antenatal depression, a few weeks later SPD kicked in. By 24 weeks I was on crutches full time, til 43(!) weeks. The SPD still hasn't completely gone.
The A.N.D. developed into PND, and 3 years later I'm only just coming out of that hole of hell 
I had the birth I really didn't want, after labour tried and failed 3 times I had an elective CS at 43 weeks (they forgot to put me on the list for 42 weeksand then insisted they should induce before performing a CS, like I wasn't in enough pain!), was v poorly cared for, I have a medical special-diet that wasn't catered for in hosp, had terrible BF advice and no effective help (though it turned out that because of the stress and trauma of everything my milk failed to come in anyway!!!)
and much much more...
and people think I'll 'forget' the bad bits and do it again...
or that it'll 'be better next time'...
I think I can confidently conclude
WE AINT DOING IT AGAIN!!!
ahhh...
that got that off my chest :)