regular/ sad day

I'm all booked for The Bead and Button Show in June. Which made me giddy for about 24 hours. Now the creepy sad feelings are returning. Actually, that may have been the longest stretch of happiness I have felt in a year. Suffering from depression is a horrible umbrella to live under. I also tend towards anxiety/panic although that seems pretty controlled by my meds. I felt for a long time that the depression was under control too. I would still get it, just maybe a few days a month. I realize the past year or so has been hell for me, so I'm adding situational depression on top of chemical but shit, why can't I shake it? I have gained about 10 pounds this year which isn't helping. I know people aren't always so upfront about this stuff but I have nothing to hide. It's part of who I am. And I was ok with that when it was a few days a month. I don't think I have made it through a day without crying in almost a year. I really want to be happy again. I do have moments of extreme happiness. The kids are always good at making me happy. But it never lasts. It seems lately that happiness disappears like a puff of smoke. So fleeting I can barely grasp it. Hardly enjoy it. Yesterday I made an effort to stay happy all day and it worked. I woke up today with the same goal but old hurts crashed in and pulled the happy away. How do you learn to "let things go"? How can I "forgive and forget" all the pain? There has to be a way to banish these feelings once and for all. At least for the past.