DNA on a child my husband say is his

I am married to a man with I don't know how many kids anymore when we first started dating leading up to the marriage it was six I only had two of my own and I love all eight they are just crazy fun but recently I have been going through a lot so I was talking to him about how I feel and what's bothering me the most only to be told in the middle of it all he got another baby out there so I as him how so he explains i don't want to sound selfish but when we talk to the mom its like she isn't even sure he is his is it wrong for me as his wife to want a DNA test done