I just don't know mama.... I rushed into and I mean rushed into another man's arms and it did not bode well for me at all. That's just my story. Then I took some time off dating and put things in perspective.... just now getting back in the dating game...
I would ask your lawyer. There is nothing wrong with having friends.
In my case it just pissed off my stbx and caused him to become irrational and fight harder for stuff and to try to take the kids away from me. He was able to use it to poison the judge against me (among other lies he told). He told the children I was trying to get them a new dad, then told the law guardian that I told the kids that. She and the judge believe him and not me. It has just been really bad. they even got an order in place that my kids are not allowed to meet my friend, etc. For us it did come up in court and became a HUGE deal. They tried to use it to defame my character as well.
I say especially if the husband is controlling, don't do it. Don't give him anything else to use as a weapon against you or another area in which to try to control you. It will just escalate any hatred or spite or whatever your husband is feeling. You might want to wait it out until the divorce is either done or far enough into it that they can't use your friend against you.
A good friend was in a similar situation with a long time relationship fizzling over several years and ending in divorce. She SWORE that her relationship began a month after papers filed/moved out but it became a tremendous issue in the trial. Her ex was blindsided by the divorce and was willing to just walk away from everything they owned. But when he found out about the other relationship, he didn’t believe her at all. It made the divorce much more difficult. And it took years of nastiness to resolve. I’d really encourage you to wait six months to a year otherwise the waters will be murky, especially with children.
I concur with those who advise caution based on my experience. I was in a brief dalliance with an old boyfriend (from freshman year of college) that started shortly after I had ended my 16 year relationship with ex (we had a domestic partnership and I terminated powers of attorney, etc.) and it became a HUGE issue ego-wise for ex, then became part of the law suit. My ex convinced the first judge of a pack of lies (that I had been sleeping with the former boyfriend the summer before I left, etc.) and I had to move heaven and earth to prove my case (the guardian and second judge looked at the actual facts rather than ex's groundless allegations and it became a non-issue, but it took a lot of work (and money) to make that true)...
Moreover, I was not ready for a relationship so soon, and those few months ended up doing more emotional damage to me when my college boyfriend turned out to be a schmuck (again, he had been a schmuck in college!)....there were signs early on but I was not in a position to see them due to the emotional stuff swirling at the time of my breakup and the need to feel loved and "stable" on some level. I think my trust in men was hurt more by the old boyfriend relationship when I was so raw and trusted (again) so easily...
I recognize that you may be in a better place than me, and better able to control your ex and how he would use the situation with respect to custody of the kids....just sharing my story!
Mom to two terrific kiddos, affirming every day that the Universe is unfolding as it should and all is well...