If she is cheating on you, you are cheating on Allah!
You are sinning and expecting Allah to bless your health and to enable
you to pray Fajr on time and perform your ibadah as usual?
Many people apostatized after being enslaved by women in haram
relationships!
Save yourself and repent to Allah, Express sincere remorse, ask Him for
forgiveness and do as many righteous deeds as you can.
Cut all communications with this woman. She is indeed bad news.