You should not keep any secrets if you think your married should be successfull;
Rape was not your mistake, if you hide this, and your husband think you were hiding this, and he feel like cheated and you may get divorce and can be charged for cheating and spoiling his marriage if that is not OK with him.
All men are not so open minded. its upto your man, marry you or not. it is better to disclose now to Avoid Future Divorce and another Heartbreak.