I'm a new Muslim and planning to move out - should I tell my parents?

Assalamu alaikum. I'm going through something important and I'm not sure what's best. I decided to move out of my family home. It's a big step, and it's not out of anger or a whim - I've thought about it for a long time and I feel at peace with the choice. I'm a Muslim woman who accepted Islam quietly; my family is Catholic and has often spoken about Islam with misunderstanding or even contempt, so I never had the courage to tell them the truth. My plan is to leave without telling them in person, maybe just a letter. My husband-to-be/fiancé (he's from a Muslim family) suggested I tell them the truth before I go. He said, “Tell them you embraced Islam and that this decision is spiritual and personal. Even if they don't understand, at least you're not hiding something so important from them.” I get where he's coming from, but it's really hard for me. My family isn't the type to share feelings; we don't have that close, open relationship. When they learned I was seeing a Muslim man, they didn't accept it and said he had “brainwashed” me. I'm worried if I tell them I converted they'll assume the same - that he forced me - when in reality the choice was mine alone. So I'm torn: should I tell them the truth before I leave, or would it be kinder to myself to avoid that confrontation and protect my peace, knowing they might react badly? I'd really appreciate hearing from people who've faced something similar or who can offer an outside perspective. JazakAllahu khair for reading.