(((Luctor)))
I am sorry to hear about your difficult childhood.
I can relate to many aspects as well. I am in DBT for the second time, and I've found it to be very helpful so far. Interpersonal Effectiveness is definitely the most challenging part for me. While I've been an active group member for 1 1/2 years, I have always had a very difficult time with both Relationship Effectiveness and Self-Respect Effectiveness.
I am slowly getting better at DEARMAN skills, using them a couple of times a week, instead of none. I'm not a real quick learner though.
When you're feeling miserable, lonely and sad, use the Distress Tolerance skills to help you get through those moments. For example, imagery really helps me. I like to imagine myself at the beach or in the mountains alone & completely safe. I use all of my sensations in the imagery as well ~ sight, sound, touch, smell, and taste. Doing this on a daily basis, makes it easier and quicker to bring yourself into a calmer state of mind.
You're welcome to ask more specific Q's if you'd like/need to. Best wishes to you!