You don't have to love your family members. Sometimes there are disagreements, animosity, falling out, divorce or remarriages. It doesn't change the fact you are still a member of the family and therefore the family tree.
Threatening legal action to the geneology website, because you discovered the incomplete tree when you 'Googled' yourself, is childish. If you'd looked further you would discover the information on the tree is available through public channels. There is a private tree (family members are invited and participate regularly)which is current.
Why after years do you continue to carry such bitterness. Your actions are mimicked by those who look up to you and have always had a pure heart. How sad. They will miss out on a relationship and opportunities because of examples, instead of keeping your heart open or asking questions. Projecting your negative thoughts onto them... No one ever pushed you away. You've always been welcome and open discussion encouraged.
You are still a part of the family. The way you choose to handle it is up to you. Professing to be Christian is talk. You should truly learn to walk the walk as well. Words are easy.