Can you evaluate my letter to clients about a fee increase?

I have a companion care business for older adults near Washington D.C. I charge $30 per hour plus $10 for gas. This is below-market-rate.

I just started this business a year ago and I didn't really know the market rate. I hate having to raise prices. It's awkward and uncomfortable. Here is my letter. I currently have 4 weekly clients.

What do you think? Thank you

Dear Friends,

It has been great getting to know you and your families.

I would happily do our work for free except, unfortunately, our society isn't set up for that type of living.

Starting September 1st 2019, my company will be increasing its fee by $5 per hour. I believe this fee is still below our market rate for companion care because other companies typically charge $45 per hour plus driving fees. 

I'm sorry for the inconvenience this causes. I would prefer not to do it.

As I said before, I would gladly work for free but the cost of everything keeps going up. 

Thank you.

Best, Brian