Marrying a girl after committing zina with her mother

Q: I have committed zina with my fiancé's mother mistakenly. She is my mother’s sister and I repent to Allah and ask forgiveness for my mistake. Nobody knows about this except ﷲ and us . I’m very nervous that if I do nikah with her daughter then the nikah will be valid or not and if I have children with her daughter.

I don’t understand what to do and currently it’s highly impossible to step back for marrying her daughter because if I try to step back there will be a big problem. Please bring out a solution for me. I love my fiancé very much and I can’t leave her. 

Are the splashes of water over non-flowing blood impure?

Q: If you pour water (flowing water) over a wound that is still bleeding a little when checked with tissue but the water falling off is clear (no detectable traces of blood) even though logically there would technically be blood in it, is that water and its splashes impure? Are the areas on your hand that are now wet around the wound considered impure?

Making intention for the person who purchased the qurbaani animal when slaughtering

Q: This year I gave my qurbaani money to the Muazzin and told him to give it to his family in Mozambique and purchase an animal for qurbaani. They purchased a goat.

My question is: In order for my qurbaani to be valid, is it necessary for the one slaughtering to make a niyyah to slaughter on my behalf?