This site should give you something to chew over:

Just scroll down a bit.
thesumma.info/reality/index.php
Plus a quote from “Theology and Sanity” by Frank Sheed, published by Ignatius Press.
From Page 122:
God, the infinite fullness of Existence, is wholly Himself in one infinite act of being, utterly fulfilled in infinite knowledge and infinite love, utterly simple, utterly single: yet not solitary…God is one, but it it is not the oneness of infinite solitude: it is the oneness of one infinite Godhead triply uttered: a comunication of infinite truth and infinite love among three, infinite self-revelation, infinite self-donation, companionship at the level of divinity.
This book devotes more than 30 pages to the doctrine of the Blessed Trinity!