Is a marriage contracted with the words, "Will you marry me?" from the man the questioner met abroad considered a valid marriage, given her knowledge that she was already married to another man? And is she obligated to inform her current husband of all the details of what happened? If it was a valid marriage, what are its legal implications?

Divorce before consummation is not subject to revocation (rajʿah) by consensus. The marriage that took place abroad is invalid due to the absence of a guardian (walī) and witnesses, and because the offer (ījāb) was made by gesture. This is a corrupt marriage (nikāḥ fāsid) that does not require divorce or annulment. Therefore, the marriage that occurred after this corrupt marriage is valid. It is recommended to present such matters to a Sharia court or to trusted scholars. The wife is not obligated to inform her husband of the details of what happened; rather, it is obligatory to conceal one's own affairs.