The mother might have used leading questions to get the daughter to say that the father was engorged, true.

But it is very weird that the daughter at her age and NOT having grown up with the father would suddenly ask him to get in the shower with him. I can easily see a nudist family not stopping joint showers even at age 5-6 but that would be a continuation of a practice begun much earlier in the life of a child. I cannot imagine that a girl who has not grown up continuously taking showers with her dad would suddenly ask for it. My community swimming pool has 5 as the threshold age when children should not go take showers and use the locker room with opposite sex parents and I think it is about right. No, a kindergarten age girl would not suddenly get this idea on her head to share a shower with her dad and especially given that he wasn't around when she was a baby and he was expected to give her baths.

Like others, I see you as making excuses for your man on account of the genesis of his first daughter. A one night stand is not the kind of a situation about which you can say that the woman used him to become a sperm donor. If a woman wants a man to father a child with her without telling the man that she has such plans, she would not count on conceiving from a one night stand. She would have an ongoing fling with him, tell him that she uses birth control and convince him not to use condoms or simply expect that he would not be smart enough to use condoms. This is possible if a woman wants to have a baby without sharing parenting with a partner and then if in addition she wants child support. But such a woman in such circumstances would not rely on the relatively low probability of conceiving from just one night together.

I had a lover years ago, now my friend, whose daughter was conceived as a result of "flirtation" with her mother who was approaching a certain age and wanted a baby. He did not tell me the exact particulars of the birth control claims she had made. He first saw his daughter when she was three. He raised her financially and with visits after that and now is a happy grandfather of two boys.

No, in your husband's case it appears to have been careless behavior on both his end and hers but she conceived and decided to keep the pregnancy and raise the child alone. Later she probably ran into financial problems and realized that she could not raise the child alone so she started desiring child support. Note that had she been a user as you like to see her, she would have sought child support from the start.

Inexperience of your man as a parent does not explain why he would get in a shower with his daughter who at that time was essentially a stranger to him. Since such a request would have been unusual, an inexperienced person would not have known what to do and by default not knowing what to do would have translated into him gently saying no.

To sum up, even though false allegations of childhood sexual abuse are very common where one parent wants to take advantage of the other parent, in your case the situation smells fishy.

What to do with it now that you are already pregnant I do not know. It is a highly unpleasant position to be in for you now and you have my sympathy.