I am going through the same, DP of 20 years telling me he doesn’t love me, hasn’t for months, was going to tell me after our holiday, so why you ask, did he tell me before the holiday, oh that would be because I caught the bastard having an EA with a mutual friend that he has always fancied, calling her his beautiful princess etc. I kind of blew his timetable apart.
This was 2 months ago, he stayed and we are working on it.
I have been through every emotion you have, panic, sadness, despair, hopelessness, indecisiveness, paranoia, jealousy, self loathing, hate, love, hope, rejection, I have been through it all.
All i can tell you is that it does get easier with time, for me it has been 2 months and I still cry, my emotions are all over the place but not as bad. You will have good days and bad days.
My biggest fear is that this has all been for nothing and he will leave anyway, my head says to kick him out, he will do this again, my heart however, the traitorous bastard that it is, loves him and over rules my head