Send Mass Email from Salesforce

I have in Salesforce the Project Object that contains a couple of fields . I want to send an email once a month to the:

- Project Contacts
- Account Owner
- Account Sales Engineer
- Project Billing Manager
- Account Trusted Advisor

Email will contain some fields from the Project level.

I tried doing this through flow but the limits are exceeded. I want somebody to help me writing this with APEX.