You dont say how old you are now? Or whether you want to compete or are still happy to hack and do the odd jump. To recapture your teenage happiness?
Lots of people on this Board returned to riding after a long gap, and others of us started late in life. Unlike most teenage riders we dont have perfect bodies, nor high levels of energy. Some of us, like you, were spurred on by illness or death and were willing to ride any way that was possible, to have the experience of riding while it was still possible.
Some of us (inluding me) had a hard time - we were humiliated or bullied and made to feel what we had done in the past was rubbish. So my advice to you would be to use your adult mind as well as your body. It is not enough to say go for it. And think there is something wrong with you personally if the whole thing is a let down.
You need a teacher who can build on your teenage experience of horses. Who can relate the way you originally learned to ride to what is now the accepted practice, and who is able to explain to you the thinking behind the changes. Then you can make your own choices.
You need a teacher who understands the possibility of riding with a less than perfect body. Who facilitates riding to make it comfortable for YOU. Rather than trying to fit you into some idealised standard postion.
If you have already looked for and found a good riding teacher, have heard of a good teacher from friends or watched someone teach, that is good. This is what the BHS rtecommend. But if you are simply enrolled at a riding school you may find that you have no control over who teaches you nor over which horses you ride. You may be lucky, but it is luck.
Good teaching is really at the heart of learning anything, and even more so in your case where you already have a good basis from the past. You will learn quickly with a good teacher - and overall it will cost less.
As far as you OH goes, mine too was afraid of the danger and that was why I never rode till late in life. Like you, we reached a point where I accepted the risk and he did too.
A good teacher will take better care of the safety aspects. I have never fallen with my current teacher, and, because good teaching is aimed at making you safe in the saddle, after six months of her teaching I stopped falling out hacking too.
But the other angle on adult safety when riding is to take control and take the decisions yourself, regardless of what the teacher says. Never ride a horse which you feel is beyond your control. Never agree to any activity which presents an avoidable risk or for which you feel you are not ready. Dont try too soon to emulate your teenage jumping. Dont feel you have to "stretch" yourself or that there are medals awarded for bravery when riding.
Buy a good helmet, consider a body protector too, make sure the stirrups on your lesson pony are the right size for your boots.
And when you have taken care of all that you can - just ride and enjoy it. It is quite possible (I know) even for grownups to behave like girls in pony books and to have a really good time on a horse.