Ok so i was happy with my girlfriend until recently. A new girl started in work a couple of months ago, approx 6-8, and i have kinda fallen for her. However this is where my problem is,

The girl from work i get on really really well with since the beginning, we are both only working to keep going this job is merely a stop gap not a career. This girl is confusing however because she seems to me to be the flirty type but then we'd never be out together as we live in different areas. Her behaviour i think is most confusing, in work we are always together and we chat about everything. She got my number from a coworker but wil only text me after i text her. She has tried to assess my thoughts of her when i avoided she decided that she 'didnt care anyway' but then said she thinks 'im cool but in denial of her being great'. She has also confessed to dreaming about me but wouldnt say in what way. Then in work she would tell me when she thinks another guy is hot and will constantly ask me who i find attractive or what i think is attractive in a girl. She also throws alot of compliments to me about my body etc. and came to my defence on occassion. In the office things have been a bit more playful recently aswell, it was hard to explain how her name and some hearts got on my arm, she also believes that she could have me if she actually wanted to. Is this just her nature and how she generally is or does she actually like me? I have a serious crush on her,

So this is my problem i believe its probably best to break up with my girlfriend? but would should i do with this girl from work?? Is she interested?? I have a serious problem here and im actually completetly lost