According to Shari’ah, a Muslim male may have four wives simultaneously with
the condition of maintaining equality among all his wives. Therefore, in
principle, you can remarry without divorcing your wife.
However, in order to avoid bitter feelings to your present wife, you should
first discuss your intentions of remarrying with her. That will save you
from the negative consequences of betrayal, etc. being possibly expressed by
her upon her discovering your secret remarriage.
And Allah Ta’ala Knows Best
By Mufti Ebrahim Desai