Should I leave my fiance or not?

Ok, it cut me off when replying to the comment down below
Sooooo anyway

Hyperthyroidism (overactive)
Excessive sweating
Heat intolerance
Increased bowel movements
Tremor (usually fine shaking)
Nervousness; agitation
Rapid heart rate
Weight loss
Fatigue
Decreased concentration

Graves' Disease
Anxiety
Irritability
Difficulty sleeping
Fatigue
A rapid or irregular heartbeat
A fine tremor of your hands or fingers
An increase in perspiration
Sensitivity to heat
Weight loss, despite normal food intake
Brittle hair
Frequent bowel movements
Enlargement of your thyroid gland (goiter)

Graves' ophthalmopathy may cause these mild signs and symptoms:
§ Excess tearing and sensation of grit or sand in either or both eyes
§ Reddened or inflamed eyes
§ Widening of the space between your eyelids
§ Swelling of the lids and tissues around the eyes
§ Light sensitivity

link

Also check into personality disorders:
Here is a website link

If I was you I would talk to him about it and if it dose work leave him and if you think it you should stay tougher for the baby the baby will not want a mom or dad that fight all the time

Dump him!

Do not stay for the child.it's only worse for the child if you continue with things like that. Some people have a tendency to change like that but if it was gradual it could be something affecting him emotionally, a disorder or something affecting his brain.
A friend of mine and her husband started having problems when he just stopped caring about paying the bills and such. Telling her "I don't care, let them take the house, let them take your horses. I'm not paying them". Turns out he had a disorder with his thyroid. Can't remember if it was graves disease or not but it killed a part of his brain that promots logic. He is now taking meds for it. I believe things are slowing getting on track.
I too have a thyroid problem, my TSH levels were extremely high and was affecting my thoughts, feelings, and common sense. Lost all care in my morals and all. Went through depression. I've been on meds for 3 years now and after the first 6 months it was like I came out of a thick fog and thought "who the hell was I?"
So, it could just be him and he changed willingly. Do some research, but when it comes to the thyroid little is written about how it affects the brain. But I would calmly talk things out with him see if he has noticed how he has changed. If he hasn't realized the change.I'd suggest a doctor.
Good luck! I wish you the best.

Wow, that seriously sucks. As much as you want to work things out with your partner, if he is not willing to put forth the same amount of dedication, what is the use? It's obvious you care about this dude and your family, but if he can't respect that, I think you should get out. Pretty soon, once your child gets older they might learn to resent them also. You want your child to have a admirable person to look up to. Having some1 that is so unemotional and closed off from you and your child would send them the wrong message. Children learn how to express love the most through the parents. If you guys can't express that toward each other and your not happy, you know what to do. In the end you will be glad you got away and moved on.

You need to tell him that you are going to leave him unless you guys work this out. It's that simple. You need to make a plan for if he doesn't come to the table. At that point, what happens next is up to you.

Good luck!