aiyo..
Simple advice la
1. if u can have a sexual intercourse while u're conscious with
other woman while u're still dating ur gf = u dun really love her
that much anymore.
2. love and marriage is a sensitive thing, anything less will
contribute to failure be it short run or long run.
Hence, it's good that u break it up with ur gf, at least u're not
hurting her further by getting married coz ur heart is no longer
with her, the marriage won't last. She'd come to realise that
soon.
I'm not too sure if u should marry ur thai girlfriend, coz u dun
really know her well enough. My suggestion is know each other
better 1st.