CONGRATULATIONS... i wont lie it is hard, my girls are 15mths apart and to be honest i found the first couple of weeks quite easy, DD1 was happy to let me tend to her sister and when i was feeding it was actually the only time she left me alone.
I made sure there were books and food for her though JIC.

The things i have found hardest are when they are both teething at the same time or if 1 is sick and the other is wanting attention, now DD2 is 6.5mths i am finding it quite nice, they interact very well with each other.
DD1 is a very caring big sister and tries to help change her nappy and gets her toys etc.

I think not matter how many you have or how close together there are always good and bad times, just remember it wont always last and 1 day at a time... good luck with it all!