I don't think anyone can really answer this for you without a big fat DEPENDS...
(FYI, i was older than you at the time of application)..
I think you definitely need SOME explanation of the poor recent science grades because that is a serious concern.
I think the explanation section is the best place to mention some of the extra stuff going on (but I wouldn't mention details or children necessarily).
Your PS is going to be crucial. It had better be kick-ass and explain why you think you are a great candidate and will blow vet school away. No one can do that for you (not that you are necessarily asking)... I do think your research experience is going to have to be used to demonstrate that the chem stuff was an anomaly.
You didn't show your transcript, but taking more higher level classes and getting As would go a long way to helping you. If you haven't done so yet, then you should start now on the chance that first semester can help you, and on the chance you may have to apply a second time. Upper level classes are a big factor at a number of schools.
Good luck.