Depression symptoms. She informed me!

Hi , I had a breakup at the age of 18 . Since then I was having some mental issues and mood swings . We have been in contact since we have a lot of friends in contact . I speak to her once in 2-3 months . Most of the time I keep myself involved in some work . It has been almost 8 years and still I couldn't get over the bad memories . Recently she informed me regarding her new relationship . All these thoughts are hitting on my confidence . Till date professionally and academically I was brilliant irrespective of many personal disturbances . Now , I'm in a stage when I feel I can never be happy again. Now and then I get suicidal thoughts but I convince myself hoping for better days . I cannot share my mental issues with my parents as I feel that wouldn't help me much , and hurt them instead. I don't even remember when I was happy last time. Kindly provide some guidance .