Another thought would be: make arrangements with your hubby on a route and leave before he does. That way you can ride your own speed and if something happens, you know he'll be along soon. Also, maybe you two can then finish together.
Also, what Annie said: if it's fear of a breakdown, learn the basics to fix it yourself and be sure you carry the basic tools to do that, which include a cell phone.
I ride alone pretty much all the time and I've just started doing centuries alone and self-supported. It was a little nerve-wracking my first time to make sure I had everything I needed, and I still could've used a phillips head screwdriver! but oh well. I Love my time alone on the bike.
Don't beat yourself up coz you can't ride his speed, you may never be able to and that's OK. What's important is that you enjoy your time on the bike and riding alone isn't the big bad wolf it looks like at first!
Life should NOT be a journey to the grave with the intention of arriving safely in an attractive and well preserved body, but rather to skid in sideways, champagne in one hand, strawberries in the other, body thoroughly used up, totally worn out and screaming: "Yeah Baby! What a Ride!"