All you have to do is, to find the courage to nicely tell her that you have made the decision to take some time to think things over, let her know in your own way that you need some space for yourself, and don't feel bad about having to say so, you don't need to explain too much, but you need to be
nice & clear. Then take your space. If you act week on this she will feel it and find new ways to hold you down. Just be honest as you were in your post and tell her the same thing you posted here, the truth in a nice way and with confidence. By doing so you will be able also to give her a lesson, since your lesson will become her lesson too for what she needs from it.
Feel free to read an article I just wrote today, I hope it can inspire you to feel the strength within to just be yourself in harmonious ways:
"SETTING BOUNDARIES" - SERIES Personal Transformation - MANY WAYS TO LOVE YOURSELF In my expertise, the basis of all struggling to be assertive is fear/concern. Relationships become unhealthy once we act from an area of concern, instead of love. Often we are not responsive to the fears that are driving our decisions to block us from doing what’s best for ourselves, and damage our relationships. However learning to line healthy boundaries offers an ideal chance to strengthen our capability to like ourselves and unharness the ego's fearful perceptions.
Signs that you just got to Set Some Boundaries:When you end up having an issue about speech communication, worry within that you have to say “no” Or that you have to explain yourself more clearly to others but don't do that, instead of finding yourselfs doing things out of feelings of guilt or obligation, trying to please others even at the expense of what is best for you, or not expressing your thoughts and feelings once somebody upsets you, you're saying to the universe that it's okay to feel uncomfortable, because you are suffering inside yes, but you are not doing anything to change that.
If you are saying “yes” to others asking of your time and energy and you’re not ready to give them your time and energy, then you are actually doing the opposite of your initial, good intention to serve them, plus you are lying to them big time. And this happens maybe because instead of offering quality time, at that point we can only offer usually our frustration of feeling pressured by them, thinking that it's more important to serve what they need from us, rather then recharge ourselves first, regardless of how they feel about our decision to do so.
Often, our habit to do nothing but suffer by giving people attention when we are not ready to do so, can create anger or resentment. This might manifest as complaining, feeling out of our own control, and consequently feeling powerless, extremely confused and frustrated. As you could easily notice at this point, these feelings are telling us (screaming inside), that we've chosen to perceive ourselves as the victim of an event creating stress, rather than stepping up with confidence to make healthier decisions based on love for ourselves FIRST, which is equal to R e s p e c t for our own way of being and feeling . If we allow ourselves to love ourselves, then we can be better lovers also to/ for others.
The truth is, we're never a victim of outside circumstances. If we are and we feel uncomfortable when not ready to say "No thank you!", Then there must be a reason that we missed within ourselves. In that case is because our Higher Selves, or subconscious mind, took us there to learn something, to boost a moral muscle, to create some new values. Everything we feel uncomfortable about, is representing a scream from our Higher self trying to teach us something, to feel better later.
See, all this happens with the hope that you first recognize the main cause of your problem, on your own (obviously with the help of available resources, if you do a little research, which will be facilitating you in the process). You must be deeply convinced that you need to do something about it, that's where change takes place. And you cannot change the situation until you walk towards change itself.
Consequently, it could come to your realization finally, that instead of always responding to frustration with frustration, you could very well read in between the lines in the midst of your dramma, enjoying the process instead of feeling that you have to sympathize with anyone all the time, let yourself, or allow yourself rather, to emphasize in the most graceful, professional, manner you know and that's all you can do.
The rest is history, once you understand clearly this concept, you are okay with moving on. You cannot be responsible for what or which choice your "Oppressor" Opted in for to be there in the first place. All that stuff, remains out of your control but allows you to feel compassion and detachment at the same time instead, for who you are dealing with.
So the question is:Are you coming from a place of inner- constant fear, or love and harmony in your actions and responses to people?
What is making you feel uncomfortable is the fact that you feel guilty of not being able to take care of your own feelings first, you lost control of that and it could feel almost as being reaped to some. Then you must act, you must regain your own equilibrium and control first, to really experience a sense of balance, confidence, courage and straight in your own life. That's most important. You cannot be a good help to someone in your presence of the momentum, if you are distant and resentful. Do the right thing to yourself NOW, practice personal transformation and you will be more helpful not just to yourself, but to others.