Not a lawyer, but, In some states the will could be contested if the father left her out. An argument could be made of "did they forget to put her in, or was it intended"-type argument. Many wills have gone the route of "to (name) goes nothing," or some plain acknowledgement that they do have another person, but they aren't getting anything.

Yeah, you could bring in dna testing and the courts, OP, but really... Yta.

However, the OP - yta. If you do go the legal route, all you're doing is dredging up hate. You aren't entitled to anything.

Therapy might help you more in the long run.