The ambiguity experienced by changing cultural context will in most individuals be resolved by discreditting certain positive and negative aspects of an experience. For example minimising the hardship experienced in the us and amplifying what he does not like about Germany. In turn your ambiguity towards life I the us has led you to discount positiv aspects and emphasise the negative ones. Essentially you are both struggeling with ambiguity amplification and negative acculturation experiences unfortunately it seems that your processes are conrtadictionary.
Strategies to lower ambiguity experience in Germany might be a way forward if not too late. Those are language acquisition success experiences close local friends. Unfortunately public welfare does not count in this respect
And by the way you probably won't find a marriage counsellor qualified or appropriate to deal with this situation. It's a different kind of councillor you need. Essentially your conflict is not a relationship conflict but you might perceive it to be as such and therefore enter a process that won't address the core issue. I have seen many similar cases and wrote my dissertation on a similar subject. I cannot help you further than pointing you in the right direction. Good luck and there are many couples like you so don't despair.
If you haven't done the interview yet, they haven't approved "everything". Approval of the I-130 or granting an SB-1 interview is only their acknowledgement of your marriage or situation, it doesn't mean they think you are actually eligible to immigrate.
Where are you now, inside the US? Where will the interview be, inside or outside the US?
If you don't want to immigrate to the US, simply tell the officer you want to withdraw the application because you want to live in Germany. You can hand them a letter saying that if you don't want to say it out loud.
You are letting your husband and his family control your life. When will you ever stand up for yourself?
If you're in Germany, they can't take the baby outside the US without your permission unless they get a German court to agree (which is very unlikely if the baby is a German citizen). If they try to physically take the baby back without authorization from you or the German government, call the police and have them issue an alert to their airports.