Need to vent

My boyfriend and I have been together for 7 months. We work together. We also work with my ex. We all work fine together and there is no drama at work (I specify "at work" because we all get together with our group of friends, who are co-workers, at our own little get togethers, and he got drunk once and started apologizing for treating me like crap and being an a-hole). My SO has this ex, who he dated for 2 years before me, and she cheated on him. It ended in disaster and he was not in a good place for awhile. I met her once before and it wasn't exactly pleasant, but there was no fighting or anything. She knew we both worked together and everything. I'm now training for a manager position at this job. She applied for a job with us, got the job, and is now in training. I hate having to see her every day, and so does my SO. We talked about it and everything. I just want to vent about this because he just wants to ignore her and pretend she's not there, while I want to complain about it. SHE KNEW WE WORKED HERE! Why would she apply? Thankfully, she looks in the opposite direction when either of us walk past her. What if she ends up on my team and I have to talk to her every day? I'm not happy about this. Also, she's been spending all of her breaks and lunches with this guy in the training class, and waiting for her ride with him outside. What if she starts saying this guy? How will the SO react to having to see them together all the time? Will he be hurt?