Feel like I’m falling apart

So first off I have 3 kids a 3year old, 4 year old, and 10 month old. I’ve been married for 6 years and we had our ups and downs I’m 22 years old and I feel like I’m crumbling and suffocating and suppressing so much feelings that I don’t even know what’s wrong anymore. I don’t know what I’m doing as a mom or wife I feel like my kids are turning out spoiled, but I know they’re good kids. I feel like I’m trying to give them a good life a life I never had growing up, I had a very abusive childhood up until I moved out at 17 and I’m worried I’m turning out like my mom. I’m worried about disciplining them I hate saying no to them on things they want and I don’t like to get after them because I feel like I’m doing it wrong. I feel like I’m trying to be strong and hold everything together for my husband and kids, but I am really in pieces. I feel like I have tried being understanding and my whole life people just crap on me. My husband did cheat when we first got together and it still does bother me he did even though I trust him now if that makes sense? It’s more of a sense of it feels like people who I trusted or were supposed to be there for me weren’t. I feel like I am on autopilot and I have no purpose in life, I feel like my life is stagnant and I’m not getting anywhere. I don’t have a GED when I tried getting it I was pregnant with my daughter and going through a miscarriage at the same time (it was her twin) then when I was going to take my test I ended up going into preterm labor and a very rough birth where she passed for almost 8 minutes and had to be brought back and we dealt with problems after that due to her going so long without a heartbeat and what not. Then I have no license because that’s another long story. I just want my kid’s to appreciate things better and listen but I don’t know how to get them too. I never had a role model in life so I have nothing to go off of other then what not to do. I take a lot of pride in my family because I work hard to keep them happy and taken care of and making sure they have a good childhood and a good wife. I just need help on what to do about my kids and how to teach them how to be more well mannered and take care of their things. I’m struggling really bad and have nobody to turn too.