I've been there too. It's very common with PTSD to spend a lot of time and energy thinking about the future what ifs, or, the past. We, as a groups don't spend a lot of time focussing on the present.
Look into what mindfulness is all about. It's a technique for staying in the present moment. It's also a great way to focus on smaller, attainable goals. Too often we get stuck thinking about gigantic goals, like: getting over it, healing. These concepts are hard to grasp and loom over us like giant mountains. By staying more in the present, you focus on getting through the day, the next meal, the next meeting, the next commute home, or whatever. By having more attainable goals, we learn what it feels like to have a success, and that becomes a platform for the next success.
In terms of reasons: think of others, just like you, that might benefit from you surviving all this crap. Picture yourself two years down the road and seeing a post on this forum from someone having a hard time like you are now. And picture yourself giving them a small piece of advice or encouragement. This can happen, and that may give someone courage to keep going. Your suffering gives you perspective and that can mean something important to someone else.
A big hug from me if that's OK with you.