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.
It is not permissible for a husband to mistreat his wife or neglect her right in sharing the bed with her (i.e. having sexual intercourse with her) as this contradicts the order of Allaah to the husband to treat his wife kindly, as Allaah Says (what means): {And live with them in kindness.}[Quran 4:19]
Even if we presume that the husband sees in his wife a conduct that he hates, he will find in her many good traits that he would be pleased with; it is for this reason that the Prophet said: "A believing man should not hate a believing woman (i.e. his wife), if he hates one of her characters, he will be pleased with another.” [Muslim]
In case he cannot stand having marital relationship with her, then he should not mistreat her, and he should divorce her in kindness.
Therefore, we advise your husband to fear Allaah, and we advise you to be patient with him and admonish him in a soft and gentle manner. If the situation gets better and the marital life continues in a good condition, then there is much good in it. However, if your husband remains as he is, and you are harmed by this, then you have the right to ask for divorce because of the harm. What people believe that a wife is not permitted to ask for divorce unless her husband beats her or consumes intoxicants and the like, then this is not correct. Furthermore, they should not consider you as being bad just because of asking for divorce because of the harm.
For more benefit on the cases when a wife is allowed to ask for divorce, please refer to Fataawa 85390 and 88479. Furthermore, if a wife hates her husband and fears to be negligent about his rights, then she may ask him for Khul’. For more details, please refer to Fatwa 89039.
As regards what you mentioned in the question about the relationship which you established with a non-Mahram man, then this is a sin. Doing so while you are still married makes the sin even graver. However, you did well by cutting the relationship with the other man but you are obliged to sincerely repent to Allaah for having done so; for more benefit on the conditions of repentance, please refer to Fataawa 87903 and 86527.
In case that man lures you to ask your husband to divorce you, then this is trying to spoil your marital relationship with your husband, and this is a grave sin; for more benefit, please refer to Fatwa 92056.
Moreover, it should be noted that some scholars are of the view that the marriage of a man with a woman whom he was the cause in spoiling the relationship with her husband is not valid. However, the majority of the them [scholars] are of the view that such marriage is valid.
For more benefit, please refer to Fataawa 86796 and 84833.
Allaah Knows best.