M.O.
Since you are asking such a personal question, I will answer you like I would a close friend...these are some SERIOUS red flags. I think you need to address these issues before you continue talking about getting married. Being married is supposed to be forever. And it sounds like you are having serious intimacy/connection issues AND anger issues, not to mention the health concerns about his heart and controlling his blood sugars.
I would DEFINITELY get into premarital counselling. If your SO puts up a fight, then he really doesn't see himself as part of the problem. He will continue treating you this way because it "obviously wasn't bad enough that you didn't marry him."
You should be in a relationship with your best friend. Your intimate partner. Someone who loves you and supports you no matter what. You deserve unconditionally love. NO MATTER if he's having a bad day, low blood sugar or stress at work - he SHOULD NOT take it out on you or your kids.
Now I'm not standing on a soapbox saying I have the perfect marriage. Of course we have our "bad days", argue or don't feel like being intimate (hey I'm a mom of three, one of which is an infant who's breastfeeding). But I am here to tell you I NEVER wished I married anyone else. I believe I am married to my best friend and someone who will always be there to support me. That said, when we do argue or snap at each other, we both know that we can say, "Time out! I don't deserve this. Walk away from me, right now, I need some space." That "wake up call" reminds the other one to CHECK their anger and apologize right now.
Just because you love him, doesn't mean he can treat you that way. It's great that he's an amazing Daddy to your kids and that he has a great extended family. HOWEVER, he needs to start working on how he treats YOU. YOU deserve and intimate life partner who makes you feel like a queen.
Here's a quote from our wedding readings:
Love is patient, love is kind. It does not envy, it does not boast, it is not proud. It is not rude, it is not self-seeking, it is not easily angered, it keeps no record of wrongs. Love does not delight in evil but rejoices with the truth. It always protects, always trusts, always hopes, always perseveres.
1 Corinthians
I always try to remember that verse when I get frustrated, angry or upset with my husband. I start by going into any conversation with love. Don't be rude, but do stand up for yourself and what you deserve. LOVE