I'm sure you grew up being taught to feel that kind of guilt or it wouldn't be so easy to fall into that being your norm now. That's so easy to have happen as many parents feel that women especially should be taught to feel that way......but we know that's NOT the way God wants us to feel.
There is no time like now to start working on changing those guilt feelings that you have been taught to feel. You will NOT be hurting him as I'm sure he will go find someone else who may not be so convenient....you don't even know who may be pushing him just to get married again...there may be something going on in his life that is pushing into needing to be married & you are the convenient one who's been hanging around feeling guilty from the first time married to him......I'm sure he will find someone else to get married to who may fit his beliefs & culture if you tell him no......you don't even have to give him a reason....just tell him no. The more information & talk you do with him, the more confused he will try & make you trying to convince you that your thinking is wrong....You thinking ISN'T wrong so there is no point in even discussing it with him......I know your wishful thinking is to have what you didn't have the first time.....but that's NOT going to happen & it's wrong in more levels than just that.
I know that you can be strong.....stand with God's strength support. That's where your strength comes from....I know it's where mine has come from over these last few years since I left my marriage. God has provided more in my life than my H ever did & finally free to figure out who I really am......you can do this also
Pray for the strength to say NO.....as you know that marriage would not even be pleasing to God let alone good for you in so many number of ways & it could even be dangerous for you.