Do I have to ask my Future Brother In Law's girlfriend to be my bridesmaid ?

Nope. Invite her as a guest.

No

Agreed, as nice of a gesture it is it's not needed. Invite her as a guest. Instead invite her to everything else maybe? like Bach and shower party?

If you are not close, I would avoid asking her to be in the WP.

I wouldn't be asking anyone at this point since your wedding is still about year and a half away. Relationships may change. Things change. But to answer your question, no, you don't have to ask anyone that you don't want to ask. There aren't really rules to it. Ask who you're closest to!

No. If they break up, your wedding pictures may be a constant unpleasant reminder. Invite people who are related to you or him or your friends

No

Nope!

Nope. Only include people you genuinely want by your side on your wedding day. When you ask people out of obligation, it ends up with a "HELP! Bridesmaid DRAMA!!!!" post on WW.

Nope. She's can be a guest. You have no obligation to her or your FBIL.

Nope. Unless you want to.

Don't have to at all. I still feel bad that my brother asked my then bf to be a groomsman, he accepted and we broke up a few months after the wedding.

Nope, don't do this unless shes one of your nearest and dearest friends!

No. Invite the very few people who are closest to you.

You don't HAVE to do anything!

You dont have to invite any one to your wedding party that you dont want to

No. And I would wait a long time before you ask your wedding party as so many things can change over time.

ETA: words

Since you are not close I wouldn't. I am not having in my bridal party the wives of FH groomsmen.

No

Nope.