CS there is such fabulous support and really detailed advice on here (with the usual odd exception), you must feel pleased that you set out the detail of the sad situation in which you are now involved and which must be overwhelming.
It would seem that you were faced with a huge shock and felt completely betrayed by your DH's actions. You have had quite a lot of time to think about where your life can now go, with the realisation of funding for that life being limited by a divorce and then you had Covid thrown into that mix. Life possibly seemed that it couldn't get any worse. It's not surprising and totally understandable, IMO, that you should see your Daughter's pregnancy announcement as one small light in the darkness and something that would give all the family so much joy and a different perspective for you.
If you can just focus now on what is happening with your Daughter by offering her more clarity and support and an unbiased listening ear, it may mean that you will be happier and make better personal decisions later.
It has been suggested that moving in with her for a while might be a great help. If it was my Daughter, I would not care what her decision was if she was 150% sure, her mind was made up, that she was doing what she wanted and she was armed with all the medical facts which might have gone towards making that decision.
I wouldn't care at all about what anyone else thought, but I cannot think for a moment that she is not going to share this with her Husband. I could understand that it's her child, but she is taking a huge risk with her relationship if her Husband knows nothing about this and, for myself, I would never want to be complicit in such a lie. It's the very worst thing to do if he's not on board and this is maybe because she knows how he would respond.
I would want to hear that she has no concerns about the risks for the future, in that she might not conceive again. If this is to be her one chance of a family - would she be so willing to play roulette with her chances of a future and successful pregnancy? I understand that perhaps you don't miss what you've never had, but what will she do in the future if her DH starts talking about having a family? This huge decision which she seems willing to take alone will surely feature in her life at some point in the future.
From everything I have read here, it does sound as if seeking Specialist help will give her the best chance of defeating the debilitating conditions she is now facing every day. The big question is, if those could be taken away, would she still want this baby? I suspect the answer is yes, because you said she was pleased ....so she owes it to herself to take the best medical advice to see if her life can be turned around and she can sail through the rest of her pregnancy without feeling so desperate, before talking about a termination.
Of course, you should not be pressuring her either way. It's not your decision to make. If you are sad that she is determined that you aren't going to be a Grandma, that's something you will just have to accept - or risk losing your relationship with her. But she must have all the facts. If she is just defeated by the horrendous sickness now, someone needs to find out if she would change her mind completely if she could only shake that off. That person is you. Giving her all the facts, maybe encouraging a referral to a Specialist team right now, before she makes any decision is the best way of supporting her.
I so hope that there's a happy outcome to this current situation and that, whatever happens, you can accept your Daughter's decision knowing that you have done all you can to encourage her to get all help. Once she is settled, this should enable you to get on and sort out your own problems without these worries and stress. Good luck.
I've got another 'keen'... Ouch!
Last weekend, in Rutland, the first statue in Britain of the late Elizabeth II was unveiled.