difficulties with clients

Hi, I'm a new editor and I own my own little production company. I feel the need to turn to some people in the biz, and thought of you guys cause you're awesome.

I have some difficult clients right now, and I am really learning a thing or two....let me tell you. First off, I'm doing a 60 second commercial that will air on DirectTV. I am new to the biz, and landed the job because the client wanted it done cheaply, and she certainly got me cheap. It's shot and edited by me, and it's way under $1,000. I don't know what I was thinking, but the contract was signed last fall, and we finally got into shooting in March, and now the edit is almost done. I was hired to do it all, but found out the night before the shoot that a girl 15 years my junior was to come along, one who assists directors in indie shoots (big whoopie). Anyway, long story short, she shows up and takes over, takes over my shots, and then takes my camera. yes, my fault for letting her, but she was bugging me over every shot I was doing, so I figured, go ahead, do it. First mistake. That was not a good day, I felt like I was there just so they could rent my equipment.

Now we're editing, and she is in the picture again, and she's trying to run the show, and she has no clue, and I'll admit, I'm being difficult to work with. I truly dislike that she's telling me what to do, because she's clueless. Her shots sucked, and her concept of editing, and everything that is involved is way off track. I'm being difficult because I resent her being there, and I run my own production gig, and it was my job. Anyway, I think I'm being unprofessional, because I'm complaining about the situation to them. When the client will say yes to a certain cut, do it this way, and this younger girl will be like, oh no, it should go like this....well, it's just not a good situation.

I'm just losing my mind. I guess I need to be told, Hey Lisa, this is the business, suck it up or ship out. Or, maybe I'm actually right in being pissy.