All perfect praise be to Allaah, The Lord of the worlds. I testify that there is none worthy of worship except Allaah and that Muhammad is His slave and Messenger.
We have already clarified that the Tahleel marriage is void in fatwa 134069; so please refer to it.
There is no doubt that you must repent from such a behavior. The conditions of repentance have been clarified in fatwa 86527.
However, this marriage does not make you forbidden for this second husband; meaning that if he wishes to marry you without the intention of Tahleel, then this is permissible. If the marriage is conducted fulfilling the conditions of a valid marriage, then it is a valid marriage, and that previous intention of making you lawful for your first husband does not affect the validity of the new marriage to him. For more benefit, please refer to fatwa 83629.
If he separates from you after consummating the marriage with you, and your waiting period ends, then you become lawful to your first husband, and the previous intention of Tahleel does not harm. It is a very simple matter.
Allaah says (what means): {And if he has divorced her [for the third time], then she is not lawful to him afterward until [after] she marries a husband other than him. And if the latter husband divorces her [or dies], there is no blame upon the woman and her former husband for returning to each other if they think that they can keep [within] the limits of Allaah. These are the limits of Allaah, which He makes clear to a people who know.} [Quran 2:230]
Allaah knows best.