In my experience and seeing what happens on the board here, separation is often, but not always, a precursor to divorce. However, if you need your space to figure out what you want, then you definitely should do what's best for your own emotional health.
What has your husband done to ensure that his behaviour stops and to make amends to the marriage?
Ultimately, separation isn't what causes divorce. Divorce occurs when one partner doesn't want to work on the marriage. One partner alone can't reconcile a marriage, no matter how hard they try, much the same as one wheel can't drive a bicycle alone.
There is nothing you can do to stop him from going to massage parlours. That is his choice to make. Whether he wants to or not is up to him. You can only control your choices, one of those being whether you want to stay in the marriage or not.
If you haven't already, read up about the 180 in the Healing Library:
https://www.survivinginfidelity.com/documents/library/faq/bs/?FAQ=11
https://www.survivinginfidelity.com/documents/library/articles/discovery/understanding-the-180/
https://www.survivinginfidelity.com/documents/library/articles/discovery/the-simplified-180/
The 180 is a fundamental shift. It presents a means for taking control back over your life, respecting your needs and boundaries, and rebuilding towards a healthier future and more enriching relationships. You can do this with or without him - you're moving forward with your life and it's up to him if he wants to try to earn his way back into your life by taking serious action to fix his failings and deal with his issues and inner demons.
Me: BH - Happily remarried.
Hope is never lost. It exists within you - it is real. It is not a force in and of itself - it is something that you create with every thought, action, and choice you make. It is a gift that you create for yourself.