Hi SR, I don't think there's any harm in seeing a L and getting some advice for yourself. There's no need to let your H know you have done this. But once you have been to a couple of free consultations, chosen a L (should you need one) and asked some key questions - you have that aspect lined up just in case.
From what you post it sounds as though your H isn't fully letting go. And because you're not letting go fully either, spending the time with him is understandably painful. I don't think it need to be a case of throwing in the towel and filing for D (just to end the pain, which of course it won't) - but it does highlight the need to work more on detachment - and GAL of course helps with this.
If you have more plans, there is less time for him to come over (because you have plans) and it gives him a chance to miss you. Plus if you are doing new things you enjoy, you become someone he knows a little less (familiarity breeds contempt of course) - and he may be intrigued about who you are becoming. He may not of course, but if you have some lovely new activities and friends, you may well feel less concerned about what he is doing.
After two years (and D finalising) I can honestly say that I wouldn't be that upset to hear news of my H getting engaged to or marrying OW, or her being pregnant etc. All bits of news I would DREAD hearing in earlier days. If I can get here, you can too.
I have been glad that I left XH to file for D. It was simple to me - I don't want to D and therefore I shall not file for D. So - forget throwing in the towel, regroup, plan some GAL - leave him to twist in the wind and keep working towards being in a more detached place. It doesn't happen overnight, we get there one step at a time.
You're doing well in incredibly tough circumstances, so do remember that x
T 13 M 7 Me 48 H 46 SS 15 BD 7.14 PA D final 5.16 (H filed)
We receive & we lose, and must try to achieve gratitude & embrace with whole hearts whatever of life that remains after the losses - Dubus