Seniors-pursue old friendship,or let it die?

peers,help me out,pls! had a friend from early teens on.corresponded all our lives,visited each other.sent presents to her kids on birthdays,xmas,etc.all her friends have busy lives.but stayed in touch.she has been absent about 5 years,now she's emailed us all.her son is going to college in the fall,it seems she took a look around and found that now that she's not as involved in his many activities,she has lost her friends and will have nothing to fill in the gap he will leave(last child to leave home.she is married,however).all of us work,have families and busy lives.only she absented herself.we were once close.but she has absolutely ignored all my letters,emails,kids birthdays,holidays,tho i have remembered hers.half of me wants to write back,and ignore her long silence.the other half of me just wants to let it be a clean break.i have'nt contacted her or her family in a year,as i felt she no longer wished to contact me.i did not expect to hear from her.we never quarrelled,she just explained she was busy.so was i,and i kept in touch with other friends with,literally 2 or 3 minute emails or occasional phone calls,but at least we made some time,acknowledged each others births,deaths,weddings, other milestones,etc.she has not been in touch with any of us till now.do i respond,or let it go?remember,despite my efforts,there have been 5 years of silence on her part,she just did'nt respond to me at all,tho i tried.