Private3

Hi,
I've suspected my husband of using coke for the past 2 years. We've been married for only 3.5 years and have a small toddler together. He started golfing with a group that had many different guys, some of which did coke, drink, or smoke.
My husband started going out every Thursday after golf which was fine. But things escalated and fast forward to these past months... I've woken in the middle of the night to find him still out... I've found coke on him 3x now and he denies it.
All this is doing is pushing me away and making me uninterested in continuing this marriage because I feel like I lost my best friend but he thinks it's my fault because I'm always mad at him. But I have plenty of reason to be in my head... I've tried just moving on and letting it go in hopes he stops... But financially it's not going well and we both make good money.
What do I do and is it really casual... I think it may be every time he goes out which sometimes can be 3x a week... ?