I received an overseas offer but my boss is really blocking my way

Hey girls, I’m really stuck in between here, could you give me some advice? I received an offer from a very good company in Berlin with a salary that seems ridiculous, but my current relationship with my boss is bad. Last month, I discreetly filed a complaint due to a harassment issue, and now, since he’s heard that I want to leave, he’s threatening me that he won’t give me a reference or anything. Do you think he could ruin my career, or should I just leave without worrying about it? I’m really scared that he might somehow block my future opportunities.