Possible megacolon - is it time to give up?

I’m looking for advice about my 9-year-old cat. He has always been a little overweight but never had noticeable bathroom issues before this month. Domestic shorthair, 8 pounds, neutered.

Here’s the timeline:

~1 month ago: We noticed some mild constipation but it wasn’t severe.

Shortly after: We were away for 2 days and he was accidentally locked in our room without water.

2 weeks ago: His constipation worsened. We saw stool sticking out, he had lost weight, and was walking funny. We manually removed the stuck stool at home and expected him to regain weight but he didn't.

This past weekend: Took him to the ER vet. Bloodwork looked good (hydrated, RBC fine, liver and kidney fine) but they said he has a severe blockage and it was “likely caused by megacolon.” They recommended either surgery ($10–15k, which we cannot afford), hospitalization with enemas + meds, or euthanasia.

Treatment so far: He has been hospitalized for 2 days, received multiple enemas with no success. This morning started on cisapride and he passed a small stool. He’s now home because the ER closed for the day. We don't have an active primary.

Current situation:

We’ve spent ~$2200 so far, and our absolute cap is ~$4900. We’re already going into debt, so we cannot afford surgery.

Our options right now seem to be:

1. Bring him back to the ER hospital tonight to continue treatment.

2. Keep monitoring him at home for a couple of days on cisapride and diet changes.

3. Euthanasia.

Questions:

Since this started suddenly after dehydration/constipation, is there a chance he doesn’t actually have true megacolon and could recover with meds/diet?

Given our financial limit, is it realistic to try continued medical management at home? Will they give us enemas and meds to do so? This is complicated by me starting a new job and neither my husband nor I will be home through the day.

How do we balance continued efforts against the risk of him suffering if the constipation returns quickly?

Any advice from vets who have seen this situation play out would be very appreciated.