Loving someone unconditionally, especially when they don't deserve it (don't take that the wrong way, please), is one of the hardest and the most rewarding things we can do.
Forgiveness is another very rewarding aspect of our lives. We may not forget, but in time, and with God's help, we can forgive.
Texasannie, I pray you hang in there. There will be a day when she comes back to you and you need to be ready with that unconditional love, especially when it seems no one else will be.