4 month sleep regression. He won't even sleep for 45 minutes

I have read others accounts of sleep regression but I feel like ours is severe.We're trying here. At this punt I'm awake every night until 2 or 3 and then my wife takes over but its killing us. We've developed a bedtime routine. Ive found out he sleeps better on his belly (won't even let us set him down on his back) and so I bought an owlet thinking at least we can know he's monitored if not the ideal position for sleep. First night with the owlet is when he now won't even sleep on his belly for more than 45 minutes. This regression is 2 weeks in.We can't hold this kid forever. He's 4.5 months now. Is he ready to sleep train? He can roll over both ways and has a strong neck. We keep nothing in the crib.Is this normal? Feeling like I have an impossible child. At this point we'll do anything that's healthy for him and us.Thanks for any help.-Sleepless and sleep addled via /r/Parenting https://ift.tt/3adB9mw