First of all, it seems that you have not forgiven her for what she did to you. While I understand that this might be very difficult, it is important to do before it destroys other aspects of your life. It sounds like it is already destroying your relationship with the Lord because you are unwilling to take Communion.
Second, you have to remember that unless your marriage is annulled, you are constantly “unified” with your wife. According to the Catechism of the Catholic Church: “The matrimonial union of man and woman is indissoluble”. It’s probably not what you want to hear, but so it is.
Third, try to focus on the fact that you are receiving the Lord, rather than thinking about your wife and your past when approaching the Eucharist.
Of course, I assume that you are not seeing other women…if you are dating/living with someone else, you are committing moral sin and should not be approaching the Sacrament anyway.