Sitara - understanding what you say about the 'other' cards... . mothers day is not just the problem... also like...
... Sweetcharlotte says about the knock on effect with other members of family, with your 'acquainted' half brothers. Me to with step parents; a real web BPD people create don't they.
GeekyGirl & zone out... yes... . a card could probably be made in the time it takes to stand in the card shop. At least then your blankish version is because it's homemade and not a 'vacant' purpose store bought one, with a cupcake on the front of it

.
I found some alternative cards online I was going to share but the photos won't drop in.
'Obligatory Mothers Day Card'
'You could have been a worse mother', with a photo of a stepford type wife
'I'm awesome. You're welcome. Happy Mother's day to the luckiest mom'
'Mom... i love you even though I screen your calls'
ha ha.