DBG is a great place for the deeds of JC. Check out Suetonius and Plutarch for more about Caesar as a person. The stories and anecdotes that they share may not be factually true, but they serve to demonstrate key parts of Caesar’s personality and can often be more true than fact with a little thought, analysis, and context. (Plutarch especially, since he writes his biography of Caesar as a parallel life to Alexander the Great).

As for modern sources, Adrian Goldsworthy has a nearly authoritative biography of Caesar as well. Worth the read.

Now if you really want to go down the rabbit hole, check out journal articles and stuff about Caesar’s language in DBG that may also give you insight into his personality and humanity.

Now, in my opinion, one can be a good leader and a bad person at the same time without the two conflicting at all, and Caesar’s genocidal conduct in Gaul makes his own ethical code (or perhaps lack thereof) quite clear. In fact, there is a classicist whose name unfortunately escapes me, who recently wrote about sociopathy among great leaders and how it being a figure like Caesar or King Cyrus of Persia almost necessitated sociopathy.

As a sidebar, I personally consider Julius Caesar to be an incredibly evil man. Many, including Goldsworthy, tend to either take a neutral stance or even champion Caesar. I’ve found reading Caesar with his war crimes in mind to be an incredibly enlightening experience. I certainly can’t tell you how to feel or what to think, but altering one’s perspective and contextualizing a reading is always a rewarding experience in study.