All perfect praise be to Allah, The Lord of the Worlds. I testify that there is none worthy of worship except Allah, and that Muhammad is His slave and Messenger.
All praise be to Allah Who has guided us and you to the right path, Islam, and we wouldn't have been guided otherwise. We ask Allah for us and you to enable us to stick to His religion until we meet Him.
Dear sister,
Know that jealousy is normal as long as it does not exceed its limits. In fact, it existed among the wives of the Prophet . But it is prohibited that jealousy pushes you to aggress your co-wife (the other wife of your husband) or deny her rights by talking to her in a bad way or doing any bad act to her. Jealousy should not also push you to try to deceive your co-wife or dupe her as doing so is among the mean and bad traits. Remember that your co-wife has the same rights as you have, so treat her as you want her to treat you.
On the other hand, know that seeking divorce is destroying your home and the home of your husband which has greater importance since your pregnancy. Asking for divorce can even include a Sharee’ah inconvenience as the Prophet said: “The smell of Paradise is forbidden for any woman who asks her husband to divorce her without a valid (Islamic) excuse.” [Ahmad and Abu Daawood]
Moreover, we warn you against disturbing your husband's life as his right upon you is great, especially since he was the reason for your guidance to Islam, hence your safety from Hell. So, try as best as you can to please him and to overcome any disagreements with your co-wife.
We ask Allah to ease the matters of all Muslims.
Allah knows best.