Juju, did your H ever have a thorough physical? The heart issues and heat sensitivity, along with the emotional sensitivity and sleep issues, could indicate a health problem, for instance hyperthyroidism, which causes both those physical and emotional symptoms.
M 16 yrs, WH62, P54 3 adult blended kids EA 11/13, BD1 6/14 PA fall 14, BD2 2/15 Piecing 2015, BD3 12/15 Separated 4/16 WH moved OW in 5/16 Divorced 6/15/17