a German child normally gives you a good perspective in Germany, even if you are not married to the father. It is good that the father's already acknowledged the unborn baby and made a custody. Later it would be important to be able to prove that he really has contact to the child. And you'll have to care about the papers (the birth certificate and the German passport for the child) quickly after the birth.
Before the birth it depends on how many weeks you have. The pregnancy itself gives you full protection 6 weeks before the birth date (in your mother passport) and 8 weeks after that. After the birth your protection will go on because the child is German. Before the birth, if it is still a long time until the safety comes, you can be at some risk, as your German child hasn't been born yet. In the moment, especially because of Corona, I don't think they can deport you to India. Anyway if your doctor gives you some paper about risk pregnancy, you can give it to the Ausländerbehörde. Explain them that you can't go now, it's too much risk.
After you've made German papers for the child, you can make an application for a residence permit after §126.96.36.199 Aliens law (Aufenthaltsgesetz) as a parent of a German child, as Meike wrote. The Ausländerbehörde can still claim that you must go to India and make a visum procedure. If they insist on this, it would be perhaps better to take a lawyer.
You can naturally take a lawyer now if you can afford it, but not necessarily. I'd recommend, just as Meike did, to look for a good councelling center for migrants in your area. They are mostly able to recommend lawyers with expertise in the area of Aliens law.