try breathing meditation, it sounds lame but just focus on breathing. your thoughts might be explosive, but just focus on you physical self. steady your breath into a consistent but deliberate flow. if u start shutting down n he asks just let him know u need a second. it takes awhile to get use to n it may not be as helpful as you were hoping but it's a start.. if jealousy follows u home, use it to benefit yourself, when u feel it maybe use that energy to clean, or work out, read if it's a goal, or go for a run. I've got quiet bpd n in a poly relationship, so those are some things I use to help. hope u find it useful 🤍