Is it true antidepressants can make aggression worse?

Yes. This side effect is more common in children and young adults, although the vast majority of children and adolescents do not become more aggressive with antidepressant use and the benefits usually outweigh the risk. Developing aggression from an antidepressant greatly increases the risk, but does not guarantee, that the person, in fact, has bipolar disorder.
Possible. If a bipolar pt is given an antidepressant & is pushed into hypo mania they night show increased irritability.