RR makes some good points if you were going straight to a complaints procedure, but in a small business corporate protocol and employment legislation are not always followed.
I'd do this:
Start looking for another job immediately, but don't tell anyone and keep it a secret. The best time to look for a job is when you're already employed. Continue at work as per usual for the time being.
Document everything. Anything that evidences what you're claiming (emails etc) Save it regularly to a datapen and keep a copy at home away from the office computer system. Don't bitch about this woman at any time and certainly don't leave anything on your computer that could be used against you. Squeaky clean.
Behave impeccably. Don't give anyone any excuses to give you a hard time.
Try to be nice to everyone including Kerry but at the same time, don't get hung up on what they say or appear to think, even if they are being a complete knob. Try to build a rapport with the boss so that when you're ready to talk to him he will give you a fair hearing. If you currently don't speak to him, just smile and be pleasant and helpful whenever possible.
When you have all your ducks in a row, try to find a time to speak to the boss (or HR person if there is one) - ask for "help with a problem of a sensitive nature"
Explain what you think the problem is in an objective and calm manner, demonstrating that you have made every effort to work around the issue but feel that you need his help to resolve it. Don't go over the top, but have your evidence ready just in case what you are saying is challenged. Remain calm at all times.
Be completely honest and ask for help.
If you do these things and nothing changes, you are already lining up another job. And if they try to sack you for complaining you can sue their butt as you'll have all the evidence a tribunal will need for a constructive dismissal case.