Darf Hamster Questions?

I started out with a female I love her to death! I got her on June 3rd in 2009 then I got a male one from Petsmart I really met to get a female...I was wrong when they had babies! They were 2 different breeds and i got 2 different breed because I thought they were both female so it wouldnt matter but they had babies the female was a Campbell ot something like that and the boy was black? Idk what breed..They had 4 babies one was huge! It was the size of the adult ones but not developed...and a medium one and an itty bitty one not even half the size of my index finger. I was freaked out because I knew they were cross breed or that the female was preggers when I got her but i don't think so she had them around Christmas time. The male got extremely aggressive and died last year:...( when they were born I couldn't tell which was male and which was female so I put it will my 1st hamster because it was sweet to the babies and I think the black one was aggressive to them but then the big baby hamster disappeared which crushed my heart because I knew it died D......: then the 2 babies were extremely territorial and then the dad died and then one of the babies died and another hamster died but idk which one?...all I know is I only have 1 hamster left and if it's the mom then it has changed ALOT with aittude which I couldvhave understood with the babies fighting and the dad being mean but with aprearance too it was REALLY fat but it could have been because it was preggers it most likely was because the babies only look like one breed and probly explains why the dad probly was a dad and just was like jealous because he always tried to make"moves" on the mom but she always got away but idk which one I have the mom or the baby? They both looked alike and how can I tell what sex it is? how can I get it used to me so I will let me look? Should I get a female if the 1 one I have is a female becaus it will work together good? Or just get a goldfish and move on?ik it's confusing Ty:)