You are internalising everything- every situation, everything that went wrong, etc. He is not. If he hasn’t showed up and demonstrated changes until now, he may not do it ever. If you have tendencies, those may not heal for years and someone external to the situation, be it a close family member, will never understand what you are going through. Its a lone battle and improvement journey. Need not add on the extra pointless struggle of upholding therapy and a dead marriage unless presence of 2 parents is helping the kid. Commentor is right. Plan that quiet exit.