Well, in general, I didn't even need to read your post to tell you that no, you're not wrong for ANY of the things you feel. We are human and we are entitled to feelings, even if they're silly or dramatic or whatever. Anyone who tells you otherwise is a crappy person. My husband and I tend to have an unspoken rule where even if we don't agree or understand the other's feelings, we don't invalidate them and we hear them out. 

Who cares WHY you feel the way you feel, the point is that you feel it and you're a couple who can work together to make you feel better. But anyways... In response to your actual feeling, you're totally not wrong. I buy bamboo/eqyptian cotton/luxury sheets for our king bed/pillow cases and $20 sheets/cheapy bedding for the kids. I wouldn't be happy with my high-quality bedding going into a child's room. 

Even if they have good hygeine, it doesn't matter lol it's the fact that it's high-quality stuff that I bought for myself/my husband. So no, you're not wrong whatsoever. 

No, you aren't wrong - if the pillows were bought for that bed, and I assume he knows you like things neat and orderly, he should have checked with you first. And if he did make a mistake, flipping out on you is totally uncalled for.  He could have said, "oops, sorry," or he could have even said, "We need to talk about how your need for order affects me," but flipping out on you was uncalled for.  

I'd get this sorted out before the wedding. 

It sounds, from your post and comments that this has been an ongoing battle. Its not just the pillow, its much more than that. The straw that broke your back in other words.

Your fiance going off on you like that was an indicator of something deeper. And now he is not talking to you. This doesnt get better, or change at all with marriage. I would recomend some marriage counseling pre-marriage. REALLY think about this.

And no - the kids do not come first. The relationship partner comes first, and if the relationship is not the priority, then everything else falls apart. The kids are the top RESPONSIBILITY - their safety and health - but as to "they always come first", well where does that leave YOU? And the RELATIONSHIP? LAST? Below the plumber?

I totally know how you feel. Early in our marriage, DH gave away pie, in my pie plate, to SS. PIE. HE GAVE AWAY PIE.

I said, "well, I'll never get that pie plate back and it wasn't yours to give away. And I baked that pie for all of us. I'd have been happy for SS to have a piece but not the whole thing." Of course I never saw that pie plate again.

HE GAVE AWAY PIE. I should have divorced him the next day.

Anyway, it's totally normal to have strong feelings over something that might seem petty. It's not about the thing itself. Your SO is much happier having you just suck it up than to tell his kids no or to trouble himself to do anything. THis will not go well unless/until your SO sees you as an equal partner in the household.

He could have said, "Oh, sorry, sweetie, I didn't realize this was important to you." Instead he gets all angry and defensive and makes it your fault. Oh HELL no. Does he have anger issues? (My exH did.) If so, he needs to get that sh!t under control and treat you like the beloved, cherished person that he wants to marry.

You both might benefit from some premarital counseling so you can learn better techniques for solving problems and handling differences of opinions. There will be more where this came from and it's NOT ok for him to blow up at you and expect you to take it, and do what he wants. You will lose your soul if you give in to this to "keep the peace." I promise.

you definitely aren't wrong. This has probably been building up for some time and it just came out in the way of a pillow. It happens to me alot. I have 3 teen kids who NEVER bother my stuff and rarely/if ever come into my room/bathroom.....but these 2 teen step kids think they are welcome to ALL of the stuff in our room and can just help themselves....my DH also thinks it is no big deal...what does it hurt...they are just kids wanting a blanket/pillow..etc.

This doesn't just go away....I would think long and hard if this how you want to live your life. I am on year 4 and it SUCKS with no end in sight.....the only end I see is me leaving.....otherwise I'm stuck with this same crap.

It's deeper than the pillow and definitely something for you to contemplate as your wedding date gets closer and closer. If you both can't effectively communicate and have some healthy boundaries and understanding about things and his children I'm afraid your relationship will suffer.

People DROOL when they sleep. Other bodily things can get on/in that pillow. Skin flakes, dandruff, bogeys, blood (I have the occasional nosebleed). I grew up in a home where pillows are NOT shared commodities. So did my DH. You can buy a pillow at Walmart for $5, FFS.

DO NOT MARRY THIS JERK.

Yes, JERK. He has no respect for you and YOU KNOW IT. Why in the world would you marry anyone who doesn't respect you??? Have some respect for YOURSELF and get out of this crappy relationship.  

he BLOWS up and is like you don't even use it and I dont want it and the kids come first and just flips out.

I said it in your last post and I will say it again, this man is not relationship material. Leave him be with his kids. He can put them first and you can find someone who will put YOU first.

I have a pillow story, as well. SD would come over with her two kids and let them play with, suck on, and slobber & snot all over my throw pillows. Gross, and seriously rude to let ones kids to that in someone's home. I cleaned and Lysoled the hell out of everything her kids touched after they left!

DH knew that it drove me up the wall, so would take the pillows away from them every time (since SD just sat there, letting them do it). He never questioned it, never said "it's no big deal, they're just pillows", or "we can clean them", or any of the other nonsense some of these men throw out there. He certainly never said, "They are my grandkids, they can do what they want."

Your SO should have your back, even in, what seems to him, the little things. His kid having that exra pillow, YOUR pillow, that goes on YOUR bed, was not life or death. So, no, the kid's want should not have come first.

Do NOT get preggers with this guy either.   I would throw this one back and start fishing again.  Namely a guy with MUCH less baggage; preferably not the baggage of another woman's biological extrusions.

NOTHING I HAVE BROUGHT INTO THE HOUSE OF SKIDS IS SACRED. THEY TAKE WHAT THEY WANT WHEN THEY WANT AND RUIN EVERYTHING. THEY LOST MY ENTIRE SET OF SILVERWARE BECAUSE DADDEEE WILL BUY THEM MORE...I KEEP MY OWN STUFF HIDDEN AND THEY KEEP LOSING THEIR CHEAP SET. THEY HAVE RUINED MY POTS AND PANS. THEY HAVE LOST, BROKEN OR THROWN AWAY MOST OF MY DISH SET. I HAVEONE HISDEN THAT I BRING OUT  FOR COMPANY SO WE CAN HAVE A MATCHING SET OF DISHES AND SOMEHOW ONE OF THOSE HAS A MISSING PIECE. SKIDS HAVE NO RESPECT FOR MY STUFF BECAUSE DADDEEE BUYS THEM NEW STUFF WHEN THEY LOSE OR BREAK THE OLD. MY 4 SKIDS LIVE WITH ME AND I CANT STAND ANY OF THEM.

OP you wrote:

How did you get it across to him that he needs to be on your side?

----------------------------------------------------------------

I never had to get it across to my dh that he needs to be on my side. We agreed on most if not all issues before we got married. I would not have married him IF I needed him to side with me about basic, daily situations.

Your boyfriend (no disrepected but this is a fact)...your boyfriend either values your things are off limits OR He does not. Right now your BF doesnt.

My dh would have said Kids, these are GoodLucks do not touch her things. Our bedroom is off limits too. PEROID.

Put wedding on hold until you AND he stand as 1 'mostly' solid voice. Dont THINK a marriage, wedding gown, a fun receiption will make it all better.

Go into your marriage eyes wide open...maybe a few sessions with a Marriage and Family Therpist too.

PS please do not be embarrassed with friends and family IF you change the wedding date. Better now then 6months down the road when you file for divorce, ok?

Best Wishes

OMG  "THINKTHRICE"---

BM's older kids rubbed poo on the walls and mucus. they were not little either. they were teens. They did what ever it took to upset their dad. It was awful, just awful

DF is putting his kids  wants not needs before you. He letting his kid have control over you and your home.  This is the best it's going to get.  Like the honeymoon stage in a relationship.  If you are disrepect now imagine after your are married.  This kid will do what he wants and DF is on his side.  
Think it's time to reevaluate your coming marriage.  Set up some test and see what happens.