In law issue

I'm not sure there's really a question here but, this is something that you need to talk to your FH about and he needs to address with them. He needs to let them know it isn't ok to treat you that way. However, and this coming from someone who is very blunt, as well, sometimes you need to learn to just bite your tongue. Pick your battles. Sometimes it's far better to just kill people with kindness.

I'm a very blunt person who emigrated to a very non-confrontational culture, where your FILs behavior is actually considered the more tactful way of getting things done. If I upset someone here, they almost never tell me to my face. Instead, they'll tell someone who they know will tell me, and I am expected to alter my behavior but never confirm for the original complainer that they were the reason why, since that conversation would be uncomfortable. My own complaints go a lot better when I deal with them in a similar way.

It may be best to think of your FILs as a small culture into and of themselves. It may not be your preferred way of doing things, but it keeps the peace if you can manage it. Just limit the time you spend with them, be civil when you need to be near them and follow their cues for the level of directness that they can handle.

I agree about talking to your FH about this. The fact that you said you are pretty confrontational is probably a big issue. It's good that you recognize that, but I urge you to consider how that attitude is likely affecting your relationship with them. If they are important to your FH then you should want things to be okay, and not let ten months go by without talking to them. You have to remind yourself that they will be part of your family too. It sounds like there is a very uncomfortable situation going on between you and them and it's something you should try to work on before the wedding. You can be blunt by saying "I know we've had our differences but I would like to work them out."

"I'm not allowed to confront them..." WTF says who?

If you're aware that you can be too harsh when you confront people, you can (and should) fix that. You can confront people without being a jerk about it, if that's what you mean by you're "too harsh" when you do have these conversations with others. All of you can sit down and talk it out like adults or you can have FH stand up for you...or both.

^^ What @Richard said!

There are two separate issues here:

1) You have someone, presumably your FH, coming back to you and telling you the things his family is saying about you.

2) You admit to being confrontational and blunt and that seems to have created tension because you are now "not allowed to confront them" - whatever that means.

Solution to #1 - FH needs to stop "reporting" to you what is being said. He also needs to not allow those types of discussions to occur in the first place, at least not allowing them to be directed at him. "Sorry, Sis and Mom, Mina is going to be my wife and I am not going to listen to you guys complain about her to me anymore. If you have genuine issue, you need to discuss it with her like adults" - that's what he needs to be saying to them.

Solution to #2 - learn some tact. That is not meant to be harsh, but if you're used to dealing with people bluntly, learning how to handle situations more delicately is a necessary lesson for you. I am also a fairly blunt person, and I know at times I come off as hard, too, so I am constantly trying to adjust and recognize when bluntness is called for and when it isn't.

I have an acquaintance who would describe herself as blunt. I describe her as rude. She wouldn't think of herself as rude, but I see her that way. She says what she thinks, and doesn't consider how someone may feel about it.

I'm not saying you're rude OP, but without knowing what you mean when you say you're blunt and confrontational, it made me think of this other person.

No one should be talking about you behind your back, that's not ok. But if you admit to being confrontational, you may have some things to work on yourself.

Talk to your FH. It's worth fixing this tension with his family because they'll be your family soon too.