Ex's

Here's the dilemma - My boyfriend and I have a business together, it's a
web based business. Lately things have been picking up, unfortunatly I
work a full time job(this was supposed to be part time,
when-I-can-get-to-it kind of web-based hobby). So here's the dilemma;
Because it's gotten busier(which is good), he decided to bring in
help...his ex-girlfriend. I have a huge problem with it..imagine that! He
didn't tell me about it until the day she started. He's not paying her
yet, she just happens to have the free time and nothing else to do during
the day. I have expressed that I am adamently against this. I would love
to go work full time on this, but I can't do it for free. So, oh great
wise ones, what would you do? What would be the best way to handle this,
without ruining our relationship? It hurts so much to know that she is
there working with him. I trust him, I just don't trust her. She's very
manipulative.