Rather than stop thinking... remove it and u can feel better. You can remove the past thoughts by sharing it to someone or by doing mirror talking.

A soul tie is the spiritual component of any relationship. Its original purpose is to draw people closer to God together. Soul ties can develop over time and can naturally become stronger or weaker as the two people in a relationship become more attached or disengaged. To overcome this BREAK up 1. Accept - Accept that you had an unhealthy soul tie . We may not always be lucky  , just like any other normal person we two have sad times ,unlucky times. 2 . Tell yourself - Believe that everyday we are getting  healed over this ,if we focus on the present . 3. Counselling  - Try approaching a therapist , psychotherapies are very effective.