Can I sue someone for money owed and legal fees, if they have been paying me but are threatening to stop?

Question Details:

My e-boyfriend owed me close to $3,000 ($2,915) but has threatened to stop paying me. He still owes me $915, but continues to hang it over my head and say he will stop paying me. He has been paying me every month, in checks, ($200/mo) and I send him an e-mail saying thank you for money paid and here is your new balance. He gave me a lump sum of $1,000 last month, but didn't say he wouldn't pay me the $200 for this month. Now that I asked for it, he said he would stop paying me and "good luck with the legal stuff moron". I have had enough and want to pursue legal action, what do I do? Important Notice