Thank you for reaching out to us.
We appreciate the sensitive nature of this question.
A chatan does need to know that if his kallah is not a virgin before they marry, and it is a halachic obligation for the kallah to tell him. This is the case even if she was never married and even if she never had relations with a non-Jew.
No one else needs to know, however, and it is typical for a chatan to agree in this case for his kallah to have the ketuba of a virgin.
We are sorry to hear of your past experience disclosing this information and understand how that would make you feel scared about revealing it again.
The usual rule of thumb is to reveal this information shortly before engagement, when the prospective husband usually has enough invested in the relationship that he will wish to continue, but has not yet made a full commitment to marry. This also protects the woman from sharing personal information with every man that she dates. There is no obligation to provide details beyond that you had sexual relations previously.
Our tradition holds people who perform teshuva in great esteem. Be’ezrat Hashem, one of the signs that you have found the right man for you will be his valuing and accepting you for who you are, appreciating the experiences from which you have learned and the ways in which you have grown.
Please let us know if we can be of further assistance.