I bought a vibrator to share with my lover but I kinda shy about it how can I approach it

Ask him if he's ever thought about using toys for double the pleasure?
I don't know what other guys think, but I like using them together.
There's all sorts of ways to use them for double penetration if you're into that.
I don't think a guy is going to feel threatened by that.
Show him how you like to use it with him as part of it.

I had this happen to me a few times. I was dating a girl for a few months, and one night in the middle of making love, she asked in a soft but sexy voice, 'do you mind if my friend comes to play with us?' and pulled out the hidden vib. I thought it was sexy and was all for it. A different girl I was dating, just came straight out with it, and asked if I would like to bring her toy in bed with us. I was ok with that approach too. I'd say you'll have to do whatever you are more comfortable with. If a vib is something new to you, I would say you should play with it solo until you are comfortable with it. Then share it with you partner.

just be like
hey I got something

and then just
pull it out from your
pocket as if it
where some
sort of pencil
or blunt

Tell him you have a new toy. Then tell him you want him to show you how it works.

OR (and this is something my husband thinks is so hot)

Tell him you have a new toy. Tell him you want to show him how it works. Make him keep his clothes on and his hands to himself - then show him how it works.

Good luck!

Tell him you got something to keep you busy when he's not around