Back story first: my best friend since 8th grade was in a tragic accident 9 years ago and suffered a traumatic brain injury. She has made an incredible recovery after having to re-learn how to do everything from walking to talking, and everything else under the sun. She is now working, in college, living on her own, etc. The only lasting effects from the injury include some noticeable balance issues when walking, some speech issues (she sounds intoxicated sometimes; her speech is slow and sometimes difficult to understand to those who aren't used to it), and some minor issues regarding boundaries, behavior, etc. However, she's my best friend, and stood beside me as my MOH when I was married back in 2008 (divorced shortly after)
So, when FI and I announced our engagement back in October, my friend was thrilled for us. She also immediately insisted that she would be in my wedding party. I told her that we weren't even close to planning, didn't know if we were having a wedding party or not, but regardless there was no way I'd be getting married without her in attendance. She then insisted that if she wasn't in the wedding party, that she would be doing a reading. I, again, told her that we weren't worried about any of that stuff right now, we just wanted to enjoy our engagement, but that I was thrilled she was so excited for me.
Fast forward to the present; and it hasn't stopped. I see her at least once a week, and every time she is set on telling me what she's found for my wedding, what songs I have to have, what readings I have to have (she'll actually try to talk to me during the sermon or readings during mass at church to point out things in the missal that she likes), what dress she's going to wear, what colors I should have, etc. I in no way want to sound insensitive, as this girl is one of my closest friends in the world, and she is involved in my life regularly.
However, I don't know who to tell her without hurting her that she will not be in the wedding party (we are having our siblings, only), and that she won't be doing a reading (I've chosen people who are dear to me and also deeply religious, as we are having a Catholic ceremony with a full mass). I adore my friend, and I worry that she will be hurt by not being "involved" with things. Due to the damage from her accident, her emotional maturity is sort of stuck at the level it was when she suffered her injury, which was an immature 18. She takes things very personally, and I know from other situations we've endured together since that time that she will get angry and hurt when I tell her.
I don't want to upset her, and if it was anyone else I'd easily know how to address the situation; but given the circumstances of her injury I am very worried about hurting her feelings. She's obviously been through a lot, and the majority of our friends from years past ditched her when she had her injury (she was in a hospital setting for almost 2 years post accident); I don't want her to feel like I don't love and value her. Any ideas?