I am meeting my best guy friend's girlfriend for the first time, may have messed up already. Help!?

Ok... So I meeting a guy friend's girlfriend on Sunday and I was wondering what I should bring her or how I should act to her to show her I am not interested in him as an item. I just got of an really abusive relationship (the hitting kind), so I really want to make it clear that I am not in to him. We have kind of flirted, kind of heavily a couple of times, but I am seriously not interested beyond friendship. I also may have miswritten things, not knowing he had a GF, which she may have read that she could interpret the wrong way so I really want to avoid drama. Being in abusive relationship really distorts how you approach situations so I kind of do not know how to communicate effectively at the moment. I have been talking to him for a while now, 3 weeks of heavy near nightly communication and known him for 6 months, and he never mentioned a GF but that is his own issue. I however am not ready for anything but friendship as of now, for years in fact; but I want to make it clear that I am not trying to steal him and am supportive of their relationship, and maybe even make friends with her. Being just newly reintroduced to nonabusive society, I can use all the friends I can get! How do I approach it so I don't make her jealous and clearly state my intent of just being friends? I don’t want to cross her boundaries and want to clearly establish that we are just friends, as he is the only friend I have as of now. Monetary funds are short so let me know something cheap but thoughtful. I am artistic and do design jewelry so was thinking of something in that department or even something below $10. I really like working with this guy and being friends, so I do not want to put that in jeopardy by making the GF jealous, seriously to the extreme of doing whatever it would take to appease her! Please Help!!!! PS........ I know it is shitty of him for not telling me about her until now but that is his bad not mine, lol. By the way, I am a computer geek and overall socially inadequate so any insight is appreciated as well.