It’s quite normal to miss something familiar, like what happens when you occasionally think about your ex. But while this is OK on one-off occasions, if it’s affecting your other relationships then it may be time for an intervention.
So when you find yourself missing your ex too much you should:
1. Avoid all communication
It is not that you are in malice with him/her, but you have to protect yourself and your present/current relationship. You cannot be in a relationship and still be communicating with your ex. It sends the wrong message to your ex and it is totally disrespectful to your current partner.
2. Get rid of all memories
It is best if you give away any gifts and delete all stored photographs. Seeing something will strike memories and that can be a trap. To avoid problems, rid yourself of all the memories.
3. Avoid going places where you shared special moments with your ex
4. Never bring up topics about ex
It is indeed in your best interest to avoid these types of conversations with your current partner. It will be used to judge you and although it may not be intentional, be wise and avoid this by closing the lid on the past.
5. Forgive and move on
The best gift you could give to yourself is releasing yourself. If it ended on a sour note, forgive and move on.