The Lv could be due to the left side never working correctly, but not picked up previously, may have got worse or could have been caused by a virus, the reason is irrelevant asn tests can't always give reasons for the cause, what is important is what tratmentment you need going forward and being monitored.
High blood pressue could be a contributory factory, but not the only reason, are you on medicaton to control it, is it hereditary or lifestyle related. If it is lifestyle you need to adapt changes to improve, more exercise, eat healthily, to reduce anxiety could look at relaxation techniques, yoga, meditation, deep beathing, do things you enjoy to switch your mind off. slow down your lifestyle. if it is hereditary lifestyle changes nay help, but will still have the underlying risk and tendency to develop as you get older.
Lv has been known to improve, usually say if no improvement within a year unlikely to see any changes, but everyone is different and no 2 people react the same.
You will have to work within your limits and adjust your lifestyle to your physical abilities, this may be ongoing if it progresses. Ie, I have changed careers twice, considered taking ill health retrment, redundancy, had to limit exercise, unable to do housework, ironing. I now qualify for disability allowance, this is not income related, so may be worth looking to see if you qualify, this allows me to pay for a cleaner and ironing to be done. My husband also has to do more around the house, sometimes not well enough to cook. My job is now desk based, so I am able to work full time, you have to find out how it effects you and your situation and look at what you can adapt to maintain as normal a life as possible. It may not effect you phyically that much as you haven't said what your symptoms are. People live a long and healthy life with it. Look at the cardiomyopathy Association website you will find lots of information on the condition, everyone is different, people can be diagnosed as similiar and have different degree of symptoms. You need to wait for further tests, it is not as bad as you think and can be managed.
Hope this helps, let us know how you get on and if you need any further info, I have had dilated cardiomyapthy since 1981, dianosed at 16 and have only deteriorated in the last 10 years, but still have a good quality of life, do the things I enjoy, you learn to adapt, but it is not easy to begin with nad quite scary for you.