Hi Vine,
Welcome to SR!
To "feel" positive you gotta "think" positive.
A little trick I learned in cognitive behavior therapy:
You control your thoughts. You decide what you want to think about. It sounds like you are already aware that these thoughts are compulsive and crowding your mind.
Just take one more tiny step and each time the thoughts come rushing in - look at a clock or your watch and say I will think about this for 5 minutes. And then let yourself think it all the way through- whatever is playing in your mind indulge it for 5 minutes. Then - time's up - force yourself to do something or think something new and different.
It helps if you have some planned "better" thoughts. Like, pick one thing about yourself or your life that you could be changing and making even baby steps towards changing. Keep that "locked and loaded" for when these overwhelming thoughts of exBF engulf you. It takes a little discipline at first but then it becomes more natural.
If you can't think of anything just replace those exBF centered thoughts with positive affirmations for yourself - you can repeat them over and over and soon the good new vibe will crowd out the old sad obsession.
Two I like:
"I now create a safe joyous future."
"The past is gone. I am free in this moment"
I agree 100% w/ Peaceteach - going no contact is important for your mental health and to break the blue spell you're under. Each time you txt each other it is like picking at a scab that has to bleed and hurt and scab up all over again. Let yourself heal!! Be an active agent of your own recovery! Take strength in each day, each moment, each new activity that you do on your own!
(((hugs))))
Peace-
B.