If this is not a fantasy post, (which it most certainly is) i'd advise against mixing up fetish with reality. That doesn't mean you cannot at least try to get a part of your fantasy to be played out.
You obviously forget about your gf fighting an ex, there is no realistic way that this goes well.
From your username i figure that you live in Italy. Plenty of session girls there. AFTER you talk it through with your gf, you approach one and you ask her to have a fantasy, semi competitive QUARTER competitive perhaps, match with your gf.
That way you minimize the risk of injuries since there's a professional involved and you also avoid animosity and hard feelings (no real antagonism, you guys don't know the girl, won't see her again etc).
