[GsUp]

After three months together my girlfriend decided that we should have a break. I was hesitant about it but agreed that if that's what she wanted I would respect her wishes.
After around 5 days with contact only once or twice very briefly, she called me and told me that she had missed me so much and couldn't believe she needed the break to see how much she loved me.
Now I am glad for this, she is a great girl and I can see the relationship being longterm.
What I want to do now though is let her know that she can't just turn the relationship off and on to her wishes. The break caused me a lot of worrying and loss of sleep (although I sucked it up and never let her know that). As much as I want her back now I feel like I should tell her that I need to think things over before I can take her back, just so she knows this is a very serious issue.
My question exactly is how do I let her know I have to think about it (getting back together) while sending the message very subtley that this is a serious issue and that she needs to realise this.
What in exact words do I say to her?