Salary

I had a final interview today, it was between myself and another person and today the interview was with the founder of the company. It was a tough interview and fairly grilling. Everything went okay until they asked my salary expectations. The range advertised was £40k-50k, I said the highest amount due to having received two promotions in two years with my current role. The founder flat out said he would never pay me that and abruptly terminated the interview and said he wished me good luck trying to get that amount. I have since found out from the recruiter that the other person in the interview, who I would report to, is only on £42k so their range isn’t accurate. I feel really down as I usually always low ball myself so tried to do the opposite today and it massively backfired. The job market is really tough right now, and it has made me realise how great and supportive my current company are. My issue is the pay is low but there is lots of potential for more progression and pay increase but it is just in very small increments. Not really asking for anything here, just wanted to vent and lift myself out of this sad mood.