It sounds as though the big problem is not the fabric per se, but the feelings it creates for you -- of pressure and obligation. I'd suggest you sit down and have a serious talk with your wife. Tell her exactly how people giving you fabric and patterns makes you feel. Tell her the feelings you have about being given fabric are threatening to ruin quilting for you. Make it about you and your feelings, not about her/your friends' actions. Talk together about hints she might drop to friends that you prefer choosing your own fabric and projects.
If it were me, I would keep it and not worry about it (if I had the space), or give it away and not worry about it (if I didn't).