Nightmares/ jealousy issues

its been awhile since I've woke up crying over something that breaks me this bad. i cant get over my SO ex. im not sure if its because he hasn't been truthful with me about it and im jealous, or if I've let the past take over me. my biggest fear is change, has been since my mom died. im tired of living in jealousy and anger. my nightmare hurt me so bad, i dreamt i took a belly of pills after i walked in on them fucking. i tried stopping them and getting his attention but i couldn't let out a peep. the next thing i know. he told me if he wanted me, he'd be screwing me, not her. how do i get rid of this overwhelming hate and jealousy. i feel like this girl has took me over..