First of all, you do not wish to act upon your impulsive desire because this would be seen as a sex offense and you would be a sex offender involved in an incestuous relationship.
There are many negative consequences from acting upon your compulsive and impulsive sexual desire. These are some of the things that you may wish to consider and then make your decision to act in an appropriate manner with your stepmom. Remove yourself from the situation (home) until you can speak to a mental health professional during the week and as soon as you can.
Hopefully have a window of opportunity in which time you can re-examine your urges and re-direct them to a more suitable person, such as a girlfriend. Don't ruin a good relationship that you may have for a lifetime with your stepmom in order to feed a sex urge that can be handled in another way! Think about what you are doing, and do the right thing!
Please let me know what you decide! -- Counselor Kathleen
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I would be willing to reduce the live discussion fee to $25.00.