part time fiancé & baby daddy

My fiancé & baby daddy to our 5w2d little one is insisting on staying at our beach house once a week so he can go to Pilates.
Re: Pilates - he said the other day going once a week is not enough to fix his back (which is why he is going). So what's the point of even going?!. There are plenty of physios in the city that offer Pilates classes but he insists on going to the place near our beach house 70 - 90 minute drive from our city home.
I've mentioned I don't think this is supportive of our pregnancy (or newborn), considering he travels for work but he responds with 'I'm fixing my back, you should be happy for me so I don't live in pain'. Or, 'this is who I am, I'm not changing' - that's a real fav.
I'm sad he wants to leave the marital home, especially when he could find a suitable place that doesn't require him to stay away from home every Wednesday night. Plus, he also travels for work most weeks so we actually don't have that much time together during the week.
Here's the kicker. If he's going to go away every week & isn't willing to compromise I think I would rather be a single mum. I didn't agree to marry a man with these values & don't know if I should go through with our wedding on 11 weeks.
I need some hard hitting advice. I'm normally strong & decisive but I feel so weak & powerless.
SO can't give me an end date to his Pilates trips because he doesn't know when his back will be fixed. He has seen a different instructor each time the past 3 weeks so it's not like he couldn't see someone else. I don't even have the energy or emotional willpower to even discuss it with him (he conveniently changed the topic). I think it would be easier to pack my bags & leave.