Deteriorating relationsip with married son?

Single mother my only son appreciated everything I did for him. I married, moved overseas: he agreed to take care of my assets/ business which provides for his family. Never has time to talk on phone,does not respond to emails: caused me to have vesuvius outburst. Our relationship is broken: I am devastated. Like a death: I have been like this for 2 1/2 months now. Help please