There is something I want to note. You are making your feelings seem like they are inferior. They matter, and you have the right to have insecurities, need time to adjust, or whatever else. That is what you feel. Your fears are valid until they subside via reassurance or of your own work from within. I do not care how comfortable you are supposed to be or should be or even what you signed up for. You are owning your feelings. Stop worrying about how your feelings or insecurities will affect anyone else. Remember that you cannot control anyone else's behaviour or how they respond. If your partner decides to back off from the relationship with your friend, know that it was not your fault. You have every right to make your feelings known and to be comfortable. It has nothing to do with limiting her or anyone that you date. Keep working on your fears and insecurities. If your partner is patient, she should be able to slow down and listen to you at the bare minimum and ask what it is that you need from her. Be it understanding, patience, time, or whatever. I wish you luck.