Had a child with a married woman. How do I establish paternity?

[netoenriquez]

Had a child with a married woman 6 years back. The boy will be 7 this year in august. She has been hidding from me for all this time. Last actual communications I had with her was her telling me that the boy is actually not mine after telling me he was and not to contact her any longer. But finally 6months ago I was able to see photo's of the boy I beleive to be my son and have recently found where they live. Child support services says they can not help me because they were still legally married at the time of conception and birth even though they were seperated. Since then they have gotten back together i guess but they have had other children. At least one of the 4 total children is biologicaly his. I know the oldest isn't and the second oldest is one I belevie to be mine. What can I do? Family Law Facilitators tell me that I will most likely be fighting a loosing battle and petitioning the court for a paternity test will most likely be a long process and would need an attorney just for that. But honestly I can not afford an attorney so I will have to do it on my own which is fine but what do I do? She threatened to leave the state if I tried to involve myself in this boy's life but why would she do that if he is not mine? I am afraind she will leave or make this extrememly difficult. Her sister in law says that the boy has a hard time in the home because the older brother tells him he is not supposed to be there because he isn't really a part of that family. He knows he is different because I am mexican and his mother and her husband are as white as can be so there is a definite difference in physical appearance. The sister in law says he may be autistic to a degree and his step father, or whatever he is does not really communicate with him. I just want to find out for sure if he is mine and if he is I need to be there for him. Any help would be appreciated.

[gemini3]

CA is a tough state when it comes to this kind of thing.  Since she was married, her husband is the assumed father for any children she has.  You can petition the court to establish paternity, but there is a burden of proof higher than just establishing a genetic connection with the child. 
 
In CA, this burden of proof is as follows ( In re Isaac C.):
 
"Under section 7611, subdivision (d), a man who has neither legally married nor attempted to marry the child’s mother may attain presumed father status if he “receives the child into his home and openly holds out the child as his natural child…”
 
The court considers his conduct before and after the child’s birth, including whether he publicly acknowledged paternity, paid pregnancy and birth expenses commensurate with his ability to do so, and promptly took legal action to obtain custody of the child. (Kelsey S., supra, 1 Cal.4th at p. 849.) He must demonstrate a full commitment to his parental responsibilities within a short time after he learned the biological mother was pregnant with his child. (Michael H., supra, 10 Cal.4th at p. 1060.) He must also demonstrate a willingness to assume full custody."
 
So, after 7 years, it would be extremely difficult for you to meet this burden.  Unfortunately, that you didn't know that you had a child doesn't enter into the mix.  There have been some efforts to amend the legislation in CA for this, and other reasons.  But, as of right now, none have been successful.