The problems between me and my best friend and why I vent about her a lot

if you want to know why I keep venting about my best friend its because we share some of the same mental ilnesess and we clash a lot , also , she has some I dont have so we struggle to understand each other , we are also very close and intimate with each other and I have romantic feelings for her but shes mainly liking me sexually so it makes a lot hard on our friendship whilst we are at work because we both want different things from each other and we struggle to meet each others needs , I sometimes overthink and get jealous or just overthink in everything whilst she overthinks a lot and thinks im mad at her when most of the time im not , its just how I am sometimes or im an bad mood but because of her , we trigger each other sometimes because we have both been through similar things , we are very similar in a lot of ways but I have serious trust issues , she dosent like expressing how she feels but shes starting to with me which Im glad she trusts me with , Shes 31 and im 22 and we are both really blunt so sometimes we upset each other , another thing , We both need therapy but we lean on each other too much leaving one of us burnt out or worst. I hope this makes sense , I lost one of my best friends who I met online then an few months after I became best friends with this one as we started working together although we known each other an year before , I still mourn every day over her and because of that its hard as im always worrying about loosing this one , we became best friends in about one month and thats the fastest ive ever gotten that close to someone and she feels the same about me , we are still trying to build and strengthen our connection but its been really hard for the both of us , we talk every day and then we are at work together all night , we also see each other sometimes before work and have sleep overs at her house , I cant say the exact reason to why we struggle so much being together , hopefully my therapist knows