Wow. This sounds a bit like my life and what I've had to go through. And my FIL could be his twin 
This is exactly why God says that a man is to leave his parents and cleave to his wife. Without this happening there would be a lot of divorces due to meddling parents. Parents just aren't supposed to interfere in their child's marriage. The biblical order of things is... God first, spouse 2nd, children 3rd, parents 4th. I'm not saying you divorce your parents, just that they don't come before your spouse. They're a bit lower on the pecking order.
Is your husband the first sibling to be married? I'm wondering if your FIL just has no experience in handling in-law relationships perhaps?
This does need to be nipped in the bud straight away, because it could eventually destroy your marriage. This isn't petty at all. I know how you feel. These things fester and just get worse over time. They affect your happiness, you begin to always feel second to your in-laws and it will put a strain on your marriage.
This is one for your husband to handle, not you. It's his father, so it's his job. He needs to put you first and set boundaries with his parents, otherwise this will go on for years and you'll be left feeling so frustrated. As your husband, he needs to be willing to put his dad in his place, even at the risk of his dad severing the relationship. You hope this won't happen, but it needs to be clear that you're a priority over his dad, so he needs to be willing to put you first and take that risk with his dad, whatever the outcome.
My husband always made his parents a priority, even some days without realizing he was doing it. His dad always had a hold on him and just would not cut the cord. I wanted to include them in our lives, just didn't want to give them the power to interfere and make decisions that were not theirs to make. We were unable to enjoy the early years of our marriage. When we took a step forward it felt like we were then taking 10 steps backwards, and it went on like this for years. Never able to progress because of their meddling. It also became clear to me that my FIL was trying to be the head of the entire family, where no boundaries exist between each married family. This just isn't God's design at all. They're religious/non believers and also a different nationality, so they do things very differently.
It was disappointing because I felt like my husband never had my back, and it was difficult to trust him after that. He seemed more concerned with obeying his dad and not upsetting his parents. They didn't seem to respect our marriage at all so it felt like a constant tug of war. Priorities were all wrong.
My FIL has always been old school and would frown at you for up to an hour afterwards if things weren't done his way, to his standards. But I'm not a clone. I'm a different person with my own personality and way of doing things. It really didn't help either that I've been in a couple of controlling abusive relationships. I never felt like I could do anything right. My confidence was destroyed and I would second guess myself on ridiculous things, while also dealing with triggers. Then here was my FIL frowning and judging me.
As for the favoritism, I know this too well. My in-laws have always offered out a rewards-based relationship, where you get rewarded for falling in line/good behavior. I've seen the manipulation, the favoritism, the clamoring for approval, competing, one-upmanship, and it's always made me feel so uncomfortable. I've always felt like a square peg trying to fit into a round hole with this family. We will feel that way anyway, since we're in the world but not of the world. It may sound strange but I've always felt like God has been protecting me from them in a way, like He had His hand on me through it all, maybe to prevent me from losing myself in it all, because it would be so easy to drift into all the craziness and get lost in it.
But I would always be the bigger person, always welcoming them into our home for the holidays, despite issues. Because they're family and I wanted to make that effort.
Boundaries were set and my FIL didn't respond so well in the beginning because he had to give up some control, but he came around and actually ended up having more respect for my husband as a result, and things did improve with them. They had more respect for our marriage. But I still had to be careful because when I gave them an inch they would take a mile.
I'm kind of typing in past tense because we're not really together right now. Our marriage just didn't start off right and this all went on for an exhausting 7 years or so. And then something happened last year that's making it impossible for me to go back to how things were. I've tried.
It's a bit scary. Change is a bit scary. I just have no idea what the future holds at all. No security there. But I'm trying to trust God with it all.
Hope this helps! Hopefully you can get this resolved asap!
Feel free to email me
