May Allah Most High reward you for your sincere repentance and your regret.

Paradise

As I explained before, Paradise is not prohibited; every single sin can be forgiven, even murder. The only sin of not forgiving is shirk (making gods other than Allah). Instead, your husband should fear Allah’s punishment for holding a grudge.

Grudge

The Prophet (Allah bless him and give him peace) said, “the gates of Paradise will be opened on Mondays and Thursdays, and every servant [of Allah] who associates nothing with Allah will be forgiven, except for the man who has a grudge against his brother. [About them] it will be said: Delay these two until they are reconciled; delay them until they are reconciled.” [Muslim]

Istikhara

I still recommend that you pray istikhara about this, as you were unhappy before the adultery and are still now. It can work out if you stay for the children’s sake, but it will take a mountain of effort, patience, and giving.

Please see these resources for improving marriage:

Course Suggestions

Marriage in Islam: Practical Guidance for Successful Marriage
Making Love Last: Prophetic Principles for a Successful Marriage

Answer Suggestions

Istikhara Prayer
Prayer of Need (Salat al-Haja)
Committing Adultery in an Unhappy Marriage
Sincere Repentance from Zina
Love, Marriage, and Relationships in Islam: All Your Questions Answered

Book Suggestions

Chapman, G: Five Love Languages Revised Edition
The Seven Principles for Making Marriage Work
Handbook of a Healthy Muslim Marriage

Article Suggestions

What Makes A Marriage Work – Shaykh Hamza Yusuf

May Allah Most High give you the best of this world and the next.

[Ustadha] Shazia Ahmad
Checked and Approved by Shaykh Faraz Rabbani 

Ustadha Shazia Ahmad lived in Damascus, Syria, for two years where she studied aqida, fiqh, tajweed, tafsir, and Arabic. She then attended the University of Texas at Austin, where she completed her Masters in Arabic. Afterward, she moved to Amman, Jordan where she studied fiqh, Arabic, and other sciences. She later moved back to Mississauga, Canada, where she lives with her family.