It sounds as if your dgs has some quite, and understandably, complex issues with his mental health. My dd is mentally unwell and it is incredibly difficult. She’s 18 and we have had 2 years of pulling her round. She is getting better, but anxious and highly resistant.
We are using someone privately, who is very highly trained in mh. The first thing she got us to do 2 years ago, and when she was the same age, was to connect with dd.
I would suggest that you do the same with your dgs. Lots of love bombing, connection, trying to entice him away from the computer. He’s going to object, probably tell you to fuck off and he hates you. The response to stuff like that is, it’s ok, I love you. And I have enough love for the 2 of us. Try to dip into his world. Would he watch a film with you. Or play a game. This is the first stage that I would do, because it’s re-establishing connection. And with connection, you have something to work with.
And at the same time, put the boundaries in. What are the boundaries? You need your write some really simple rules, which you write down and present to him. And not too many right now, otherwise he is unlikely to comply. Find maybe four or something. So pick the ones, which are most needed. Put a copy on the fridge. And write on this that you will turn off the WiFi at x time. You’ve got an almighty battle coming.
WRT going to college, it sounds as if he won’t do anything willingly, or be told. You’re just going to need to sew seeds here. If you find the information about which local college would accept him and possible courses, then you could suggest something to him. Try to find a moment, when he is calm and available to connect and just say something like, I’ve seen x college is offering course an and b (check availability first). It starts on y date in September. What do you think? Then leave him, come back to him a couple of days later. Tackle it lovingly. Ask him if he’s thought about the college stuff.
Have you ever told you dgs that he may be your grandson, but your love for him is one of mother to him? That to you, he will always be your son. And you love him to the moon and back. I am just thinking, perhaps a key to his feelings, is to allow him to feel how he does about the rejection from his birth parents (effectively this is an adoption situation in all but name). I just think it would be useful if he could see himself as a person, inside your little bubble.
Have you spoken to him about how his parents are with him? How he feels about that? That it’s ok to be hurt or not to like them. And very importantly, you need to be putting your hurt to one side for all that. The hurt from him and from your dd. And you’re going to need some counselling yourself as has been mentioned, to be able to really park your feelings and not let them spill into your relationship with your dgs. So that you can remain loving and calm.
The reaction your dd has had to this all would make me think she’s also very hurt, that she wasn’t given what she needed emotionally either, when she gave birth to that tiny dot. Did you just take over and she fell into the background? I’m wondering if she felt very rejected. 13 is a very tricky age from a brain development perspective and it seems there there was some quite black and white thinking, that she’s take forward. That one is even trickier due to her age. And she’s a grown woman now.
Are you the sort of person, who just gets on with it and doesn’t give out much love? Because if you’ve been this way, due to some very tricky circumstances, this is how things have ended up this way. And you are the parent. And the changes come from you first.
And please, get all the support you can from a social worker, from mh charities. And anyone, who will listen, including the school, who may have some ideas for you. If you can find someone at school, who is interested in his wellbeing, that could be a starting point today.