To say I'm enraged is an understatement. I'm using a throwaway, but even if he finds this I can safely say that I don't give a shit.

I've been with my boyfriend Tom for eight months. I've always known Tom is a staunch atheist which is fine by me; I was raised in the church but have since become agnostic. Aside from Tom being somewhat preachy about his beliefs, but never disrespectfully, I was fine with everything.

My mom has cancer that has become terminal. She's always been a firm Catholic, yet I can tell that she's afraid of passing away. She's been very emotional about leaving us and missing us. I've been setting my own emotions aside and helping her with hers and reassuring her and just giving her all the care and support she needs. While she's bedridden, she likes listening to that country/pop-ish 'God is Great' type of music that's somewhat cheesy but somehow brings her comfort. Am I a fan of it? No. But if it makes my mom feel better and brings her comfort, I'm all for it. Myself and my sister have no problems letting her keep it on loop and letting her talk about heaven and such.

My sister and I are trying to coordinate taking time off from work to stay with her during this time, and Tom offered to sit with her and help her during the times neither of us could get away. Great! He's stayed with her twice and I didn't detect any issues. Fast forward to yesterday afternoon.

I went to mass with my sister to bring communion back for our mom while Tom stayed with her incase she needed anything in the morning. When we came back, I noticed my mom was in tears and Tom was sitting there with a very nonchalant expression on his face. I immediately asked what the hell was going on, and my mom vocalized to me that Tom had been shutting off her music and when she asked him to turn it back on he refused. He wouldn't give her the iPad back so she could turn it back on. Instead he sat there and envanglized to her about how since her passing was getting closer, it'd be easier on her to accept "the truth", with the truth being that there's no God and there's nothing on the otherside.

His presence was upsetting my mom so I told him to please leave, and he immediately kept trying to explain himself and tell me that my mom was exaggerating and she had it all wrong, and that it wasn't true, and all I did was tell him to get out and we'd talk about it later. My sister took it a step further and hurled a cup at him while he was leaving.

The more time that passes the angrier I'm getting. Tom's blowing up my phone telling me that he was just trying to help her and that he didn't mean to upset her and that he wants to be there for us, and I have him on mute (oh, and he's also angry that my sister "assaulted" him). I don't know if I want him near my mother. Hell, I don't know if I want him near me. My best friend (who is friends with Tom) hinted that I was overreacting to the situation and said that he means well but just executed his plan "poorly".

I need an outside opinion on this. I don't know if I can come back from seeing my mom in tears as she's dying of cancer.

Edit: He's now left a long voice mail in which he claims he wants to come over and personally apologize to my mom. Unsure if this is a good idea or if he's really seen the error of his ways.

tl;dr: Boyfriend decided to deprive my mom of her religious music and tell her religion was foolish while she was bedridden. I'm beyond angry, best friend tells me unreasonably so.