I know exactly where you are all coming from!
I have recently split from my baby's father partly due to his constant comparing me to his ex's (he has 2 daughters by 2 different women)
First time he compared me was when I was struggling loads with ms and fatigue, and not really being able to do much, he says "Tracy was still laying paving slabs up to a week before giving birth" well good for her, but other than that being really dangerous and irresponsible in my eyes, every pregnancy is different!
I always REALLY made the effort with his Daughters, and to be fair one is fantastic. The other really got on well with me, and I faked it with her, but she is a real little brat. Nearly 3, always gets her own way, is VERY rude, swears, bites, really nice.
I even made the effort to get on with his ex's - even after one sent me constant death threats for the 1st 4 months we were together.
Finally finished with FOB after it turned out he was still allowing his ex access to his bank accounts and paying her phone bills, ringing and texting her constantly, to the point that she actually sent me a message on facebook asking me to get him to leave her alone!
Didn't help that 4 months into our relationship, I found out he had been ringing etc begging for her back (he left her for me) and then tried making out it was all a ruse so as he could carry on seeing his daughter!
So much better off without him!