Help me! I start to become jealous!

One of my best friends is in love with a guy and I start to become jealous of her happiness !

I feel so bad, I should not, I'm not in love with him but I feel so alone because I'm single and I hate feeling like that while she's enjoying her beautiful moments.

I know i'm totally selfish and it's bad buuuuuutttt....I don't know what to do!!! I'm even afraid of what I could say or do to her impulsively because of jealousy 😵