true…from a ethical point of view and yes honesty is great… However, If you do tell… ( remember you have the right to be silent) then accept the consequences (him leaving you…maybe) but I mentioned before, a good man who is meant to be your husband will understand that you sinned and repented and both of you can move on to your future together.
honest men also respect honest women..so who knows..if Allah wills it…then if you do end up telling him your past if he asks, then he might be OK with you being honest and won’t leave you.