I am glad you could assert you weren't "punishing" him by stating it's not fair for him to flit in and out.
However much space you give him, however much understanding you show, he has to help himself by seeing a GP and taking properly prescribed medication and/or arranging counselling. Too much space can be alarmingly close to becoming a recluse. If he rations time spent around you and DCs, does he also avoid others?
I agree with other posters, look after yourself. Any chance to think of yourself, pick up any hobbies or pastimes, fix up to see your own friends, when time permits. Many partners and parents put their outside lives on the back burner - I've done so myself - it won't stop you missing DP but gives an added dimension.
Have you anything planned for yourself on Friday?
Going back to work won't be the jolliest distraction but it will give structure to your week.
Next week it would be nice for you to have a block of time without the DCs. As has already been observed, going from a familiar two parent set up to a new arrangement whereby you are without warning now sole resident parent is a big shift, on top of the emotional earthquake. Space is quite a luxury with 10 and 6 y.o. DCs in the mix.