I believe marriage is about working to overcome anything. Both our parents have been married for a long time and we both believe in marriage
This was my philosophy too. It kept me in an abusive marriage and several abusive relationships because I believed that it was necessary to work to overcome anything. Thankfully (due to MN and lots of reading around toxic relationships) I learnt a great deal and now how much better boundaries.
My stbexh put work first, then his family, then his friend, then our children, then me. In fact I'm not sure I even figured at all.
Your fiancé is telling you who he is, listen.
He has told you his mum comes first. You are not a priority.
What happens when his mum passes away? He is going to be unable to deal with the grief as his mum was the focus of his life. He will be totally lost and it will be up to you to try and pick him up and put him back together again and get him through it. He is setting himself up for such a massive fall.
I think it's great that he is supporting his mum but it's obsessive and totally inappropriate to be at this level. Is this going to go on for the rest of her life? He's not doing her any favours being there so often and she's probably sick of seeing him.
I lost my dad and helped my mum through. We were always close and became closer. She's had a few serious injuries and needed my help since but my children always came first. (My stbexh had left by then).
Both you and your child are suffering from his lack of attentiveness. This won't get better. Is that what you want for your child?
I have every sympathy for the period issues as I have extensive endometriosis and used to take morphine for period time pain. However I soon learnt that even with 2 children and the inability to do much except lie on the sofa and put a film on, my husband was not going to put me first and take time to look after his children because I was too ill to do so. I too was accused of being controlling.
Don't marry him. Otherwise you'll be back here asking us how to get out of your marriage. Or go ahead, and know that you will never be happy because you will always come second, third or whatever. You're about 4th on the list now aren't you? You'll stay there unfortunately and spend your life miserable. Good luck.