We all collect a lot of things we do not use. Go over your sewing area and really think about what you use and what you don't. We moved to a much smaller home for the same reason and I gave boxes of quilting books and notions to my daughters, friends, and took some to Quilt Guild for freebies just to make sure they got to someone who would hopefully enjoy them. Odd fabrics went to the thrift shop. Yarn to a friend who crochets all the time. You won't feel so bad about getting rid of stuff if you know someone else will use it. Be tough! No place for being sentimental. If you make a mistake you can always buy more. I even gave away three sewing machines!