I'm thinking of letting a woman stay with me and I expect her to sleep in the same room with me
Why are you expecting this woman to sleep in the same room as you?
I've known her for a while and she has always been in my heart.
You should not automatically assume that another person will want to sleep in the same room as you. You need to take other people's desires and expectations into consideration.
I don't understand why it's an issue.
If you have offered to let this woman stay with you, she has probably naturally assumed that you meant in her own bedroom. Since she is likely making arrangements based on your offer, you need to let her know that you intended for this to be an intimate arrangement. Give her the chance to decide based on what is true.