What do I do?

So last Sunday my mum came round while I was at work. My fiancé was home alone and he told me my mum stayed for a while. He told me that she said it was really hot outside and she wasn't wearing a bra.

I don't know if this was casual talk or if she was hinting.

Ever since then, she's been sending him messages with a kissy face emoji (😘) and she thought I was working this weekend and asked if mt fiancé wanted company. Thinking I wouldn't be there.

She is a very sexual person (a man eater)

I honestly think my mum is trying to have sex with my fiancé behind my back. I'm feeling so down and betrayed.

I know my fiancé wouldn't do anything if she tried anything with him, I trust him completely. And he feels uncomfortable about my mum because of this vibe she's letting off.

Am I worrying about nothing? Or do I have the right to worry? And what do I do? I don't want to confront her because of course she'll deny it.