Need to have a tough conversation with a friend

Hey guys, I need your thoughts!

I need to message a friend to tee up a time to have a tough conversation.

They were/are my best friend of 6 years. We used to live together until I had a falling out with one of our housemates who is a bone-chillingly evil person. (I won’t get into those details here!)

This friend still lives at the same house (with said evil person) and has sent me lots of mixed messages around our friendship. For example, they sent me a birthday card a few months ago saying I was still their “bestie” and telling me how much they love me but don’t invite me to things and rarely message me.

I’m confused and deeply hurt. I am struggling to not ruminate on this constantly.

Help!

I need to send this friend a message to tee up a time to talk. Do I mention in the message that the reason for us to meet up is to talk about our friendship? Or do I keep it more general and bring it up in person?

This friend still lives in a sharehouse with someone I find to be extremely unsafe. What kind of boundaries do you think would be fair to me to have?

For example, I want to know that the personal things I tell my friend about my life are kept private and not told to this person who will potentially use that information to hurt me.