Hi there!

While there are limited written sources on the life of Antinous, the main ones are Cassius Dio's Historia Romana (Book 69), the Historia Augusta (Life of Hadrian Pts 1 and 2), and the Caesares of Sextus Aurelius Victor (I couldn't find a good English translation to link).

Other mentions of Antinous can be found in the writing of Athanasius, Hegesippos, Prudentius, Clement of Alexandria, Tertullian, Justin, and Tatian.

Outside of that though, much can be inferred based on the thousands of images we have leftover from Antiquity. Antinous appears as sculptures, casts, on coins, in relief, and in inscriptions. Historians like Lambert can trace the aging, relationships, and even personality of Antinous through these images.

Sources:

Life of Hadrian/Historia Augusta

Historia Romana Book 69

If you want a more detailed breakdown of these sources as they relate to Antinous, here's a great journal article by Sarah Waters

I hope this helped!