How to deal with disappointment and never being able to get my hopes up

I met what I thought was my souls mate 4 years ago.  Obstacle after obstacle, reason after reason, chaos after chaos has made the last 4 years a weekly roller coaster!  A year and a half ago my partner finally begin taking medication for her ADHD.  I know believe she is under medicated and under treated, but chooses to rely on just her one time doctor appointment and 4 pills a day to state she has made changes to better things and anything beyond that is just me wanting to change everything about her.   Her personality changes daily,  for 3 days she is completely in love with me and wants us to be as close as those sappy people in the movies, then, without notice (like a blink of an eye quick) she begins to say the most hurtful things and starts to act distant and secretive.  She will go from saying "baby, you are my best friend and I don't want to spend a day without you!  Let's make plans for this weekend.  What should WE do?" To..".we don't have to spend all our time together, I have other people in my life you know!  I don't have to like everything you like, I am not like you! I don't want to be so co-dependent on each other", etc.   and these times seem to be around me looking forward to plans that were made....something we agreed on together and then she pulls away.    Lately even saying "I am allowed to change my mind!  You go if it is so important to you!  I only agreed to go because it is easier to just agree with you then to be my true self".   Usually, when plans are made I don't count they will happen.  I have become accustomed to preparing I will be going and doing in my own and not even trusting she will be joining me or joining me enthusiastically.

but the other Friday seemed different and it has just broke my heart to, I worry, no return.  I had been going to the beach a few times in my own (a beautiful hour drive there) and she was feeling sad that she never agreed to go.  So on Tuesday she said let's cut out of work early and head to the beach for a few hours to relax and connect, watch the sun set and eat at the restaurant we love so much!  It will feel really good to get away and just escape together! (We have been under some tremendous stressful situations lately).  We talked about our escape all week! :). It was great!!  It appeared she really wanted to go!!  Come Friday morning I confirmed with her that she was still up to cutting out at 3:00 and just heading off to the beach...not needing to pack a bunch of stuff....and just GO!  She yes!  Absolutely!!   I checked in at Noon....still good?  Not too tired?  Need a nap?  Still okay not to pack a cooler or anything?  Yes!  Still good and excited!  I actually dropped my walls and allowed myself to get excited and feel joy and happiness and I felt synergy with her!  We were in tune and on the same page!  This was something we both liked to do!!    At 3:10 she says in an all too familiar tone, "I just don't get why we are leaving SO LATE!  We won't have any time to pack food or drinks or anything to sit on and why would we drive for an hour just to spend an hour at the beach and then turn right around and drive an hour home?  I just don't get it!!!  Why can't we go tomorrow!!!  I just don't get it!!   

I will admit, that my balloon being popped stopped my ability to calmly bring her back to understanding.  I began to feel all that joy, hope, synergy and connection disappearing and I started to act desprite!  I said "WE planned this together, you suggested you!  This was something we had in commen, something WE do!  You picked the time because it worked better for our jobs, etc.   she just became more and more adjitated and angry and stuck.  I said "we were going to watch the sunset and eat at our restaurant".  She said, "but why leave soooo late,  why not just go tomorrow, etc etc etc....  I knew tomorrow would just as much as a crap shoot as believing today would work, so that promise just didn't help.  She sleeps in until 11am then takes 2 hours to wake up and so it would be close to 3 anyways.  And was so much more then just going to the beach!  Does anyone else get that???   

I began to cry and she yelled at me "OK!! Let's get in the fucking car and have an awesome time at the beach, for an hour!!!  Some how the entire thing blew up into a huge fight.....I mean huge!  One of those fights you never want to have, with threats of leaving and bringing up old baggage and her telling me she never tells me her feelings because I am a controlling bitch who only ever wants it her way!!  There were threats of physical abuse....or you know..what do they call when animals make them selves look bigger to make the other feel weak?  Posturing I think?  Items got thrown.  I was told non of her friends like me because I make them all nervous and they think I control her and I make her life a living hell.  It just fell apart!!  I was soooo devastated!! And when I would tell her that she just mocked me "oh....I am soooo devastated".  We ended up fighting and staying away from each other then fighting, then staying away from each other, etc all weekend.  The things she said to me during the fight sting to this day and have caused a rift between us that we are just barely getting over today.

we do love each other!  We do want this to work and when it is beautiful for both of us (I believe).  But I just won't make any plans with her or get my hopes up for anything!  What she says on Tuesday or Wednesday can change once the weekend comes and making any sort of reservations or traveling plans or buying tickets or even having people over CAN be such a mistake and a big let down!   I know she wants to do better with follow through and being accountable.  But any thing can happen, and usually does just at the last minute!  

How do I deal?