This IS so important to realize! It is a concrete accomplishment very unlikely to be reversed. It only goes forward from here. This was the result of the Bernie revolution. It should be taken as a sign of progressive strength to make change.
You are so right to say we need to focus on Congress. One of the things which concerns me about some Bernie voters is they seem hyper-focused on Presidential politics, when in reality the real power sits in Congress. We need a Congressional revolution. Your other movements, such as Black Lives Matter, are equally important causes to continue.