Bd left me today at 8 months pregnant

So my bd cheated on me with his so called baby mama and he claims that his daughter that they have together is his but she looks nothing lol or him what so ever so because I told him to show me a dna test that way I don’t have to be taking care of her kid cause she doesn’t I want to be comfortable because my bd has lied and said her oldest daughter was his so that’s why I never believe him