Obtaining DNA test results

Okay yall I have a dilemma so my bf was taking care of a child for 2 years he says the childs mother would tell him "I'm gonna take Janae (the baby) to see her real dad any time they got into a heated argument well its been about a year since he says they took a DNA test and found out the child wasnt his well the mom posted on Facebook that hes lieing and needs to take responsibility for his child this that and the other. It got me thinking I've never seen the DNA test no one has but him and supposedly her his story to me was the picked up the baby one day the went to get the DNA test done it said she wasnt his so he took the paper to the girls house she looked at it and said "I knew" and kept the paper. But since seeing her posting that hes lieing I've been pretty bothered by it like what if he isnt telling the truth why doesnt he address the issue to her why does he constantly let her bash him and not say anything about it. I understand being the bigger person but this isnt the first time shes posted about him being a shitty father. We also have a 4 month old together that he takes care of all the time. Should I address the issue with him? Should I ask for him to get a copy of the DNA test to let me see it? What should I do please help no harsh comments either please