alittlesad
Like everyone else on here, I hope you are OK and I hope your dh proves us all wrong and pays back your trust in him.
The fact that there was something seriously wrong, that his behaviour was odd - perhaps unloving?- led you to question him. Don't forget that. He didn't come to you and tell you that he needed more time together, did he? He didn't come with solutions or questions. He just made life so hard, you had to find out what was wrong and then hit you with a double whammy of rejection and tears.
I think Maleview and Math have it spot on about 'being in love'. That's just weird after anything more than 3 years. Are you honestly supposed to have butterflies in your stomach, be off food and text 100 times a day for the rest of your life? God knows I've fallen in love loads of times, but I wouldn't marry and have kids with the tossers poets/artists/pot-smoking daydreamers. Most of us allow things to run deeper that are perhaps less exciting, but more real. That's what you build a family and a future on.
The red flags are there. He has withdrawn, he talks about not 'being in love' and he is weird with his phone.
Whatever this turns out to be (and for me, the kindest thing for you would be a state of mental anxiety on his part), the only advice I have for you is to remember that your needs are exactly as important as his. So whilst he is deciding whether or not his 'in love with you', you are without a caring, supportive partner. And your children are without a family father. It's up to you how long you decide to put up with that.
Please, in all this heartbreak, remember to put yourself first.