Committing adultery is one of the grave sins which is promised evil consequences in this life and the hereafter, but Allah forgives all sins including adultery. He said in the Quran:

 

“Say, O My servants who have transgressed against themselves [by sinning], do not despair of the mercy of Allah. Indeed, Allah forgives all sins. Indeed, it is He who is the Forgiving, the Merciful.” Az-Zumar 39:53)

 

You have already repented your sin only seeking the pleasure of Allah. There must be a kind of test from Allah to confirm the sincerity of your repentance.

 

You should concentrate on how to please your mother, show her the best of your behavior and consider the great harm you have caused to her. By showing her good conduct,  she will definitely change her attitude towards you.

 

Allah Almighty knows best.