I am wondering if anyone can relate to my situation.
Yes, and I spent a long time not leaving my apartment.
I don't think being alone is necessarily unhealthy or problematic. But isolating because of a mental illness is something very different to making a personal choice to avoid people out of mere preference. It's avoiding symptoms of an illness, rather than choosing something that just makes you happier or more fulfilled, and that's a big difference.
One of the problems with isolating because of mental illness is the tendency for that to put pressure on every other symptom, as well as feed other mental health issues that love to piggyback off PTSD (anxiety and depression are PTSD's 2 best friends). Everything gradually gets worse, even though it's an attempt to just make things easier.
It's a lot like if you decided not to sleep to avoid nightmares. That may nix the nightmares for a short period, but all your other symptoms would escalate, and your coping skills would quickly deteriorate at the same time.
For a PTSD approach? I'd come at this from the stress cup angle for good short term gains: what can you do to empty out that stress cup? That's reducing other known stressors (eg. Leave work earlier, take on less commitments or let go of some with kiddo, cancel some stressful upcoming engagements, ask people to help out with certain obligations etc), and increasing stress-reduction stuff (more exercise, better sleep, better nutrition, etc).
This kind of PTSD issue is also
very often greatly assisted by Anxiety disorder treatment approaches (and that's where I made the most gains, probably). Starting with therapy modalities - getting back into CBT and DBT behavioural habits, behavioural activation stuff, and ACT skills (particularly mindfulness and value-driven actions).
If the Stress Cup is a good general analogy for reducing/managing ptsd symptoms, the Anxiety version is probably SUDS (on a scale of 1-10 how distressed am I right now?). They're very similar. SUDS is about constantly checking in with your personal distress levels, throughout the day, and modifying behaviour to reduce your distress when it starts increasing
before it gets out of hand.
At the same time, SUDS means including daily habits that reduce your baseline SUDS level (how distressed am I, usually, when I wake up each morning?). Regular guided relaxation (20-30 minutes a day, taken like essential medication), regularly practicing your deep breathing, and other activities that help get the central nervous system to chill the hell out (which can be anything from yoga to gardening). Reducing that baseline SUDS level is, for Anxiety, akin to emptying out our stress cup. That builds up a much better tolerance for those stressful human interactions.
The truth, for me? Was there was profound depression in the mix at the same time. And that made doing all those basic daily mental health care activities extraordinary hard. If you've got that in the mix? Speaking to your treatment providers about any depression support that might be available can, potentially, make it a shiteload easier to do the things that need to be done in order to manage the PTSD stuff successfully.
Just my 2 cents, based on my own experience of something very similar. Hopefully something in there is helpful.