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.
If what you mentioned about your husband is confirmed that he committed those sins, then he is very wrong. It is even more abominable for these things to happen from a man who has two wives and who is a seeker of Islamic knowledge. Such a person should be pious and should rectify people, and he should not be corrupt and corrupt other people. However, if he sincerely repents and it becomes clear to you that his conduct improved, then you should live with him in a kind manner.
However, if it is confirmed to you that he continues to be on that condition and that there is no hope for him to abandon those sins, and you fear harm by staying with him as a wife, then you have the right to ask him to divorce you because of the harm. Rather, it might be that it is better to ask him for divorce because there is no good for a wife to stay with someone who is on this condition. Nonetheless, you are not sinful if you stay with him as a wife even if he continues to be dissolute but you are obliged to advise him.
The following matters should be mentioned:
1- It is not permissible for a wife to investigate whether or not her husband has an affectionate relationship with another woman, because this is a kind of spying and it is forbidden.
2- In principle a Muslim is innocent, so it is not permissible to think that he wants to commit Zina (fornication or adultery) or that he committed it without evidence.
3- A husband is required to live with his wife in kindness; Allaah Says (what means): {And live with them in kindness.}[Quran 4:19] In case he mistreats her or treats her harshly, then this contradicts living in kindness.
Allaah Knows best.