I have a phobia. It because of stress?

I an currently under medication for hypertension and pcod. The moment from when i have been prescribed medicine to lower my bp i have been very depressive as i am only 19 and having hypertension .This has led me to stress and i have thoughts that is this serious or am i going to die? I dont want to think about it but i just keep thinking and when i hear bout the deaths by heart attack or stroke or cardiac arrest , i keep thinking whether this is going to happen to me or not. I am the only child i have no one to share thus to and even if i do no one will understand how i really feel. My bp is under control now and sometimes it goes till diastolic 90 but is it because of stress? I am 66 kg 5'2 height because please help.