Help

Hi, just looking to rant or some advice. Me and my partner have a one year old and are a happy family. We have been together for 4 years but in 2022 we had a 4 month break and both slept with different ppl when we got back together I got pregnant very quickly. It had always been up in the air wheather it was his. Scientificially the dates add up to him & I never doubted she was his. And we left it at that. He is her dad, he is a good dad and loves her to bits does everything he absolutely can for her and always puts her first. He has her name tattooed on his heart and is the best dad I could have asked for my daughter to have. Lately mine and my partners relationship isn’t the best there’s lots of distance and I am just feeling very down about life in general. Finically we are struggling we are working our asses off and just not getting anywhere. Everytime we see family everyone says that she looks nothing like her dad it has been playing on my mind and as she grows the more she looks like my ex ( the guy I slept with while we were on a break). I have no idea what to do she looks exactly like him and I feel so guilty. Do I do a DNA test. But what if I don’t like the results ? Do I tell him ? What if he leaves us? Am I shpppsed to tell my ex? Who isn’t a very great guy and neither is his family I wouldn’t even want his family to see her. But what about my partners family who is so inlove with her and would do anything for her? I don’t want to ruin anything for my daughter right now she has 2 happy parents and 2 happy family’s. What if the results come back and she has a broken family & two dads??? I’m so lost and feeling so depressed about this I think in the bottom of my heart I know my partner is not her biological dad. This would seriously break his heart o don’t know what to do. Do I just pretend and carry on with our life?? What if it comes up in 5 years and all unfolds then. Do they deserve to know the truth?? I don’t know. Guess I’m just looking to have a rant some advice maybe. Has anything like this happened to u? :(