Discussions

The best advice I can give is to start setting boundaries with your sister-in-law. I am assuming because you don’t want to hurt her feelings that she is not being mean. So you can set boundaries gently and in a positive manner by thanking her for her advice/direction and say I will take your advice into consideration. Then make your own choice as to how or what you do.  
If she is being really pushy simply use the following statement inserting your own word: sister-in-law/name when you say ....insert.... I feel .....insert.... I would appreciate it if next time you......insert...  
An example might be... Name when you tell me what to do it hurts my feelings and I feel pressured to do things I don’t want to do. I would appreciate it if you would stop telling what to do all the time.  
Or something like that. You can change it up to suit your situation. I suggest writing it out on paper a few time to get the wording right. Hope this helps.  
 
Btw you may need to keep setting boundaries so be consistent with her.

Set your boundaries, but be prepared for the case where things may get nasty.  
Your scenario doesnt explain a lot but depending on the type of person she is, and the family dynamic, it may just go south.  
Its up to you to decide what you can live with and go from there.

Whatever the situation, it sounds as though you have to be blunt with her and deal with the fallout whatever it might be. Being concerned about not hurting feelings and being gentle in your answer will not solve this sort of problem.  
 
I see that there are possibly two situations that you are encountering...and maybe both. It is too hard to tell which it is with such a little information. Here are my solutions to both. They work well.  
 
1. If the only problem is that this woman is opinionated, tell her that her that as much as you respect that she has opinions, that constant sharing of those opinions is not appreciated. You can think for yourself. Tell her if you want to get her advice, you will certainly ask. She will be offended initially and maybe for a while, but set that boundary and stick to it.  
 
2. If it is a matter of a controlling sister in law, this is what I have done with a similar type of person. It will be hard. You will most likely offend her, but that is okay. She is not respecting you. You need to set boundaries with a controlling person like this. If you do this, you will feel like the bad one for a while, but you are not bad for sticking up for yourself. I found doing the following extremely freeing. It was totally worth it and puts you in control in that situation.  
 
First of all, always be on guard.  
 
Secondly, just say NO. All the time, EVERY time. Give no reasons why. That only gives an invitation for her to manipulate you. It might sound extreme, and yes, it is, but it will set firm boundaries. I encountered a "guilt trip" type of response from the person when I said no, and she also used someone else to be her mouthpiece and tried to "guilt trip" through them too. I still said NO. It was hard.  
 
If you can get your husband on board, get him to do the same with her. Often a controller or manipulator will try to go through him too...or through someone else that might hold sway over you.  
 
The key is to be consistent. It will get worse before it gets better. Hang in there. When she finally backs off after quite some time (you will know the time), be willing to consider her thoughts, but be just as ready to reinstate "NO" if the situation requires.

I tell these kind of people that there is more than one way of doing things. If that works for them, great, I will take it into consideration. As long as your end result is what you want, there is no right or wrong way. One person was getting getting really pushy with me, I used this on her, no hurt feelings, she stopped dead in her tracks.

It’s up to you to stop letting her tell you what to do. Let her know that you value her opinions, but it’s your life to choose what you ultimately do.  
My sister in law and I were close at one point in time. But she too became bossy and demanding. If I didn’t want to do what she expected me to do, she treated me terribly. Would start ignoring me at the drop of a hat. If I hung out with people she no longer liked, same thing. If I didn’t want to celebrate holidays how she wanted ( which I did for many years), same thing. Sometimes I want to celebrate a different way, more like how I was raised, but her way was always expected. She went through a nasty time, I took the brunt even though it wasn’t my problem.  
I finally just had enough and reached my end point.  
When I was told we were doing something without even asking anymore. I was done. I haven’t seen her in over a year, and don’t really care too. I don’t hate her, I just don’t want her in my life.  
I’ll never stop my husband from being with his sister though, as it’s his sister. This isn’t his fight, however I wish he would’ve put his foot down more and told his family the truth instead of lying about why we weren’t doing what was expected.  
I’m much happier now that I don’t have to tiptoe around her.  
I chose to walk away.  
If you want to maintain your relationship with yours, talk to her and let her know how you are feeling. If she gets mad, and cuts you off, maybe that’s for the best. You should never have to tiptoe around family.