I made a mistake and cheated my husband, I slept with other man what can I do?

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.

Indeed you have committed a grave major sin and an obnoxious one. Zina (fornication or adultery) is among the gravest sins if committed by an unmarried woman; how much more it is if committed by a married woman!
She accumulates disobedience of Allah and disloyalty to her husband. Moreover, she pollutes her bed while Allah has satisfied her with what is lawful but she engaged herself boldly in what is forbidden.

You should return in repentance to Allah, determine to never practice it again, avoid being with men, going to bad places, and mixing with bad people as much as possible. Do not watch bad and immoral films.

You should keep asking Allah's forgiveness and do good deeds as much as possible. If you do these acts, Allah may accept your repentance, have mercy upon you and forgive you this grave sin.

Allah knows best.