Do I stay or do I go???

I have been married for 24yrs,(me,uhhappily) not in love, but my husband is a very nice person. Met an old boyfriend I haven't seen for about 26yrs. He is separted, and w/a girlfriend...still loves and misses me we live 1200 miles apart I am so confused of how I feel. Don't have much trust in him but my heart aches for him still.