child responsibility

I met a girl and we had a relationship.She was separated (but not legally). During our time she admitted having other affair aside from me. Then she became pregnant and told me that the child is mine though I'm having doubts if it is really mine because she admitted having other affairs. And even one of the guy said that he will claim the baby if the girl will just say that it is his. She keeps of insisting that it is mine and even asked for financial support from me. There were times I'm giving her money just to shut her out. Until she gave birth, she told me I abandoned them. Then after a year, I visited the child but I never signed any birth certificate or any documents that shows I am claiming the child. Will there be any problem for me in the future?Because there are photos of me and the child together.Maybe she will use it against me for financial support or anything like that. Thanks