It can be so hard to control those kinds of feelings. You have actually taken a big step by simply realizing that what you're feeling is a result of your own issues, and are not due to any misbehavior on her part. I think what curlyq suggested is a good idea...do whatever you can to be nice to her...even if you don't "feel" love for her, do as much as you can to act that way. I know it sounds odd, but I have often found that acting like I feel a certain way, even when I don't, can actually shift my feelings. You may even want to try things like just saying to yourself, "I love my sister-in-law"..."I am glad to have her as part of my family"...again, even though you don't think these things now, telling yourself them over and over again may actually start to shift your feelings.

Good luck...it may feel like an awful struggle, but from what you say, you really want to conquer these feelings, so I'm sure you can.

mj