This must be sorted out by a spiritual director.  One person who punishes himself for sin may be acting nobly, while another might be exhibiting psychological issues.  That's what spiritual directors are for.

I would go a step further.  Even fasting beyond what is required by the Church should take place under the guidance of a spiritual director / Confessor.  I've known people who were practically neurotic with regard to self-punishment even in the form of fasting.  That's why the rule of St. Benedict generally forbade doing things beyond what their rule of life required.  Often it comes from pride.  When you fast according to Church law, this is done under obedience.  Otherwise, the motives might in fact be harmful.

Instead, do what several retreat masters have suggested by cheerfully accepting all the trials and crosses that come with daily living.
Read the book of Job for good advice on how to accept the trials of life.
Study the book of Hosea if your wife has imperfections, and rejoice that she is not a prostitute.
Above all, give thanks and praise God for all things. Never curse.
When someone curses you, bless them.
When you receive bad news, bless the Lord as it could have been far worse.
Say short prayers throughout the day, like "Lord, Jesus Christ, have mercy on me a sinner."

Increase your prayer life by saying prayers morning, noon, and night.
Ask your confessor to recommend good spiritual reading books.
Read the Epistles and Gospels that are appointed for the day.

In addition, start reading the Bible, especially the Psalms of David, and try to memorize certain passages so that you can pray them whenever you are tempted.

Above all, pray that you may not fall into temptation:

O Heavenly King, O Spirit of Truth, O Comforter, Who art everywhere present,
And fillest all things, Come and abide in us, Cleanse us of all impurity,
And save our souls, O Good One.