Indeed Scorpio Moons tend to hold on to memories (usually negative emotions) for long because Scorpio is the sign of survival and its instincts for self protection are strongest of all-therefore remembering what caused you grief is a natural protective mechanism for you. Scorpio is the most vulnerable sign emotionally(even though they may not show it) because the evolutionary goal for Scorpio is to develop emotional security in the person. But the process of its development can be painful-one needs to pass through these emotional ups and downs and crises so he/she can learn to build inner security no matter what the outer circumstances are. This comes with age naturally and the emotions settle down.
The Scorpio Moon can be very much helped if you have planets in the two sign immediately before and after Scorpio--Libra and Sagittarius--if you have any of these 5 planets there: Venus, Mars, Saturn, Jupiter or Mercury then these planets act like buffers for your emotions and can really ground and stabilize you emotionally.
Scorpio Moon person will benefit a lot from having a small ritual every day(like a short prayer) in which he/she sends love and forgiveness to the person or event that caused him/her grief or resentment. If you cannot visualize that, then just ask every night God/Your High Self/Christ within you, to do this for you.
Initially this will not feel natural but just keep doing it(even if it does not feel heartfelt) and within a few weeks you will start noticing big emotional shift-it is usually gradual but it makes a world of a change. The key is to be persistent with this occult exercise and the energetic transformation will come about for sure! A regenerated Scorpio Moon has amazing potential for success in life because the driving force behind it is profoundly powerful and when it is not longer going towards resentments and regurgitating pain, it becomes a combination for wealth and achievement.