You know what, fcuk it. If I were you, I'd pick up the phone and call her exactly that. That way you will not be stressed out when the text is coming (and you KNOW it is coming) and you'd also pull a 180 (being assertive).
And trust me, it will feel darn awesome. If she starts giving you lip about it, you just say W, I see your point, however my mind is set. Good day!