Don't know if I can do this!

Hi There,
My brother's toy poodle had 4 pups recently and though I kept saying no to owning a pup, after 8 weeks of my brother asking and seeing how cute the pups were (and how much my daughter wanted one), I caved in and said yes to the last of the litter needing a home.
It's been a week since the pup came to our house and I am having major second thoughts which I feel terrible about! I knew it was going to be a lot of work but the reality of it seems even more crazy than I anticipated. I have 2 young kids (ages 7 and 4), 2 needy cats who are not getting the attention they are accustomed to, and this pup who I am constantly watching since I am trying to housetrain him. My younger child, though he likes the pup, seem upset since the pup is more apt to nip and bite him. SO, my house feels completely like a zoo.
I know it's only been a week and it'll probably get better but I am wondering if I am right for this in the first place! I am not enjoying this chaos and wonder if I ever will... I know, I sound really awful and I have been feeling terrible for feeling this way!!!
Plus, I just found a tick on the pup which makes me really scared since I am afraid of him bringing ticks and fleas to the house that can affect my kids and cats! Am I putting my kids and cats in harm's way? We already took the pup for his first check and he has had Revolution but how effective is it to control fleas/tick for the whole household?
As you can tell, I've never had a dog and am quite confused. I look at the pup and he is so cute and trusting - he really needs to be in a home where he will truly be loved. I take good care of him but I feel too stretched to enjoy it all and can't help but feel like I am exposing my family to potential harm with ticks and fleas. We have open space outside with deer and other animals so the cocern is high for ticks and fleas...
Should I start looking for a better home for our pup or am I being irrational? Thanks in advance for your help and for reading this long email.