Husband 45 mid-life crisis??

We have been married over 20 years, he's 45. I have been busy with the adult kids and grandkids, he's been busy with a coworker that's 20 years younger. Only on the phone, talking and sending txts and "other things", he's put us in debt $20k buying her gifts and giving her money, the past year on/off. She has another "boyfriend" that's married and works there too. My husband is devastated after he has realized what he's been doing, he breaks down daily because of the pain he has caused me. Says he was in like a fog, NOTHING he told her was true, she doesn't even know who he really is, he made up a whole new life that he has. She knew about me though. He's going to counseling and trying to get help to figure out how he let this happen and he swears I'm the love of his life and he don't know how he let this get so out of control. I guess I'm asking, is this normal for a mid life crisis? Our marriage now is better than ever, we both were neglecting each other, and we realized that.