Special needs SIL driving me NUTS

Guys I need to vent. I don’t have any friends and I don’t want to get spewing negativity into my husband so I have to get it out. Even if no one reads this. I am currently the primary caretaker of my SIL. She is 19 and has autism and FAS. She is also a product of incest so she has a lot of developmental delays. She is emotionally around 6 years old but has the mouth of a 16 year old. I was an ABA Therapist and I am in school for Clinical Psychology so we moved in with my SIL and MIL so I could help with her. I have her from 5am to 5pm every day, just her and I (my son is in school). Guys I’ve burned out. It comes with so much emotional suppression because if you display upsetting emotions even if you handle them appropriately, she has a meltdown. So if I stub my toe, or if I’m stressed about finances, or something personal is happening, I have to completely suppress it. I can never just allow myself to have emotion. This morning my tire was low and I got stressed and she ended up needed consolation and I couldn’t even locate an air pump because I was trying to calm her down. It’s constantly like that. I’d like to add that I am super great with her and we have awesome rapport. Which sounds great right? It can be. But that also comes with her following me everywhere. She follows me when I go pee. She comes in my room and piddles around until I wake up. She moves my mail around. She’s constantly tattling on my son. She is constantly touching me and is down my neck at all times. Yes, I set boundaries with her. I’m very firm with her and I implement ABA style goals and redirections throughout the day. I know how to handle her and her behaviors. However, it’s different when your “professional” life and your personal life get weirdly mixed. If I’m on a call, she asks who it is. Why I’m talking to them. Etc. if I don’t answer her then she’ll Google it, ask my MIL, etc. She’s 100000% in my business. I put a lock on my door so she can’t go in but because of my son, if he is out of my room and I’m in it, it’s unlocked and she uses that as an opportunity. I’m done working with her as a “staff” in January and I’m going to find a job. It’s just until then, I’m going absolutely crazy. I’ve reached a point where I can never have my own space. There is no “clock out” time. It’s not an hour session and it’s over. It’s my life. When I bring it up to my MIL, she’s like “Oh I know, sheslike that with me!” Or “How do you think I feel?” But it’s NOT MY CHILD. I didn’t sign up for this. I know that sounds mean but it’s true. Please know I love her and I do have such a great relationship with her and I handle her like I’d handle any client (with some bonuses of course because she’s my SIL 😜) but she just takes over my entire existence. From the constant screaming at everyone and cussing up a storm constantly, to requiring 100% of my attention, to breathing down my neck and questioning my every move. I know my husband is worn down from hearing me talk about it constantly but I’m so worn down I had to type it all out.