When i moved in with my girlfriend her daughters were 11 and 14. I was scared out my wits too. In the beginning i felt like i wanted to pull out my hair sometimes in frustration but it all worked out. I have ZERO patience with almost everything and i tend to run if things go badly. Somehow it all worked out tho and now 6 years later life is good in that regards. My main advice is find someone(even post here if need be) so you can vent about your day. That is what always helped me get thru it. Dont let the frustration build up and realize you are gonna make some mistakes no matter what. Plus kids do some downright neat things sometimes when their not busy being kids One time when the youngest was around 13 i was having a terrible day and she made homemade cookies just for me. She didnt want anything in return,it wasnt a bribe. She just wanted to brighten my day. Hold on and remember these good things as well and try to remember em when you feel like your getting way too frustrated and remember you get to go home at the end of the day.