Praise be to Allah.
If a thrice-divorced woman gets married to another husband, but has the intention of getting divorced from him so that she can go back to the first husband, there is a difference of opinion among the fuqaha’ concerning that. Some of them regard it as coming under the heading of tahleel (a marriage aimed at making it permissible for the woman to go back to her first husband), which is haraam, and some of them say that her intention does not affect anything.
See the answer to question no. 131290, when it says that the opinion that this is haraam is more likely to be correct, and that if the woman gets divorced she does not become permissible for the first husband.
You did right to repent and go back to your husband and ask him not to divorced you, because it is not permissible for a woman to annoy her husband or ask him for a divorce (talaaq or khula‘) unless there is a reason that makes it permissible to do that, such as if he is mistreating her.
But if this husband divorces you of his own accord or in response to your request because of his mistreatment and his speaking harshly to you, without the intention of making it permissible for you to go back to your first husband, then it seems that once your ‘iddah has ended it will become permissible for you to go back to your first husband, with a new marriage contract.
And Allah knows best.