I moved my Mother to AL and now I feel lost and some guilt. When do you get over these feelings?

Certainly you have some regrets, but don't confuse that with guilt. You did the right thing by getting her to a safe place. You can do more for her by stepping back and not going every day. Change her focus to her new friends.
Mom was all woe is me, but then we went there one day unannounced and caught her having fun with new friends. Boy did she look surprised, like a kid with his hand in the cookie jar.

Helping her with the transition might help. Can you spend time taking her to activities, helping her get acquainted with the other residents? If's there's music, art or pet therapy, make sure she participates. Bring a radio or portable CD player for her "apartment" and bring her favorite CDs as well. Make sure she knows how to use it. Put on a CD when you arrive and when you leave.

These shared activities will help you as well.

I don't know if caregivers really get over the issue of moving a loved one into a facitlity; I think the guilt issue is always there, at some level or another.

But you have to balance it with the reasons you did move her there. Could either of you have continued safely in the prior arrangement? If the answer is no, then you've done the best for her. The trick is in acceptance of it, and that's not easy.