Tips for self confidence please!

I need to have self confidence, not having any is messing with my relationship. My brother in law messaged my partner randomly and said "im at a hot af chicks house right now" and I just felt horrible. I don't know why. Maybe because my period is 2 months late (not pregnant) and I'm a walking mess right now. I know it's something so minor to be sad about but, it really knocked me 😔 Tips on having self confidence / self worth?

Thankyou!