You can learn more about what your differences are if you continue to speak with them, and do some research on what the issues are that they disagree with the Catholic Church on...research the Church's views with Biblical support for their beliefs and do the same with the Protestants beliefs and their Biblical support.
Of course this is better done in person, so you are limited.
I was reared Catholic, and my husband belonged to a non denominational Community Church, when we met...his family...mostly mom, had the family change denominational churches a few times.... Baptist, Episcopal and the Community Church.
Anyway, like all protestants they were taught that Catholics were bad or not really Christians and a whole bunch of other Southern traditions said about them. And honestly, I think I was trained to believe only Catholics were true Christians....not directly....but indirectly...with rules, like you have to marry a Catholic.
But they loved me, and I loved them and their son!
And religion was important to both of us! My hubby...boyfriend or fiance at the time, gave me a Student Bible to read, which had explanations for each book, before you read it, and during the read here and there where it became tough to understand...
as a Catholic... though hearing the Gospel and other Scripture my whole life in Mass and catechism, I never owned my own Bible, to hold and read myself, and even scribble notes in, as my mother in law did...her Bible that she had for at least 50 years has notes that old from when she heard preachers, preach on the passage, in Sunday sermons or Bible study classes.
She was a walking Bible, any questions I had on something she could lead me directly to the Bible verses discussing the topic...
To make a long long story shorter, we learned from each other, around the kitchen table, with Bibles in hand, that we were both, Christians. I was even able to convince her that some things she believed about Catholics were simply not true....using Bible verses! She even apologized for all the years she thought evil of us from her training before she passed onward.
Dear Lord I miss her!