It looks as if you’re getting some sleep, which is good. I only have a daughter. But I agree that this behaviour needs to be dealt with now before he is bigger and stronger than you. My dd is 12 now and sure knows how to escalate things and a lot of the boys her age are definitely physically stronger than me.
I agree that your ds is testing you and will continue to do so. I hope he is calmer tomorrow. What I have always told my dd is that I always love her even when I am angry with her or when she is upset with me. Nothing will stop me. So the I hate you was always countered with I love you. We have an agreement that however upset or cross we are with one another, even if I’m shouting, she can always ask me for a hug. When she was younger, I repeated that I loved her often and made up the silly phrase that if she didn’t exist, I would have invented her. Idk how old she was but I could ask her the question of what would I do if she didn’t exist and she would tell me the answer. Now that she has a phone, we text little emojis, I can write and tell her how proud I am of her and how much I love her. As your dcs have these already, you can send them little love texts too and remind them why you are so proud of them. I’m a very tactile person, so I stroke her hair and kiss her on the forehead a lot.
It sounds as if you have a big heart. One thing I’ve learned is that your dc will deeply hurt you and tell you they don’t love you and all manner of things. I know it hurts terribly. When it first happened, I made a decision that I knew dd would say all manner of things to me, consequently, I wouldn’t get upset as I expect her to say things as I know she is letting off steam. If you act wounded with them, it will only increase their guilt, pain and shame, which will make the outbursts more likely to happen or for them to retreat into their shell.
As for the punishment, I agree removing tech for a week is a terribly long time. Dds friend had her tablet taken away from her for 6 weeks once and that didn’t work either. Consequences, especially natural ones work better and if your dcs know what they are, they will be easier to accept. With dd when she was younger and more volatile, removal of her most favourite item at that particular moment was 24 hours and a week for serious offences, such as violence. For her it was her prized shoes or a doll. It sounds as if it could be tech for your ds.
I think tomorrow is a fresh day and that you should be looking to ways you can apologise for making mistakes and for their father being flaky and you will never be like this with them. They need the message repeated that you are constant. If you model good behaviour, it will give your ds the ability to model it too. Then talk about how sad you are that your ds got so upset that he did x and y. And that you’re here to talk and cuddle because you are so sad when you see him so very upset and you want to help. Then tell your ds that at the moment, having the nerf gun is a bad idea and you are going to keep it safe for him until your ds can show he is able to treat you well - natural consequence. I’d use it as a symbol of his behaviour and maybe you can eventually make it into a little in joke between you about not getting it back until he’s 21 at this rate. Anything to to take the tension off. After you’ve had a chat, do aright, what fantastic thing shall we do today? Or I’ve planned x. Above all else, try and do something fun today as a family to get past the upset from last night and tell them you’ll give them the tablets back for half an hour this evening or failing that tomorrow morning.
As for the comments from other people, my suggestion is a sticking plaster for now and will work if consistent. But it does sound as if your ds, perhaps both your ds’s need some therapy and you’ve had some great suggestions. I do hope you have your family to support you. Being a single parent sounds like a lonely place and one, which requires very robust mental health so make sure you find a little bit of you time as well. 