How much space should I give her?

We cannot be together because of extenuating circumstances, hell of a mouthful of BS going on here on one side! Whenever the scenario you've presented here, it's usually because one of the potential suitors is using the other until their ideal suitor comes along. Meaning you are not hers sadly. Girls/women don't want what they call a wet behind the ear type of boy/man. In short, if you're the type of boy/man that's sensitive, caring and generally considerate with all affairs and dealings you have with your peers they'll consider you too emotionally challenging and somewhat clingy in nature - in short a nerd nor an Adonis! I know that you're probably smitten by this girl, but trust me she's using you so, in less you're okay with this kick her to the kerb. This action will however increase your popularity with her "as nobody likes rejection" but that's all this heightened need to gain your attention is. The tanks not dry but I think sometimes less is more. I wish you the very best whatever you decide.