Welcome to the Wefugees community and thank you for your question.
1) In a situation like that I can only recommend to get in contact with a lawyer. Someone that is specialised in cases like that can take a much closer look at it and give you the best advice.
2) Unfortunately it is not possible to marry in an embassy in Germany. The one and only authority that is competent for marriage is Standesamt.
3) There is one problem with that plan: You only have a Duldung so you are not allowed to travel because you have to stay in Germany until further notice.