Answer: In Yoga, we are always finding ways to let go rather than hang on. Expand rather than contract. Open rather than close. Let Divine run the show rather than our ego run us. You have invested time, energy and passion but that investment went into your identity, the false one that you are not. You are not that role. You are a completely free being without identities. This is the problem with investments into anything we interact with such as raising a child, building a business, buying a car, building a life that we think we are in control of. The ego invests hoping it can own and control something. This grasping, manipulating, directing is how the limited self needs to behave in order to cover up its sense of lack.
The solution is to aim for directly experiencing your fulfilment as opposed to investing energy into trying to cover up your lack. Turn your attention to love and care for yourself. This issue of others destroying your project is there because you invested your energy there. You put your energy into something external to you. You need to balance your direction of energy. It should always include yourself. When you see all is YOU, then you do not leak energy out. You can work on a project without setting yourself up for disappointment. Pull your energy away from it until you no longer feel affected by what they do. Maybe you need a full cut or break from the project and them for a year or so. Then maybe revisit after you have withdrawn all your investment energy. You will see the project from a more empowered place and maybe even contribute this time without fear of loss.
Another thing you can ponder is perhaps they are doing just fine with the project, you simply have a narrow perspective of how things should happen. Whereas you could open to other possibilities and allow them to play with it until they come up with something that works. You can instead feel proud that you got the project on the go and they will carry it further and now you can lay back and relax while they do all the work.
You can let go and enjoy rather than get anxious and assume they are doing it wrong. You can trust they have another way that will further your creation. See it positively. In order to see it positively, you need to let go of how you think it should be. That letting go will be a great relief for you. I encourage you to LET GO!
Ultimately everything is undergoing constant change, all creations dissolve into the creator again and again. So you need to identify as the Creator, not with the creation. Let GO and be the Creator. Let the creations come and go.