My feelings go up and down every day since I found out my husband will take another wife. Is this normal, and when will it ease?

Feelings that come in waves after big news are normal, because the heart is processing loss in stages. One day you feel strong, the next you are shattered again; this is not a sign that you have failed, but a sign that you are human. Grief does not fade in a straight line, and there is no fixed timetable for it to ease. Do not force yourself to be 'okay already' before it is time. Keep up the basic routine: prayer, sleep, eating and a little exercise. On heavy days, it is enough to do what is obligatory and be patient. With time, prayer and support, the waves become less frequent and smaller. See mental health.